1. Peony rust

　　[Symptoms] After the plant is infected, round, oval or irregular brown spots appear on the leaves, the leaves turn pale green, and yellowish-brown lesions grow on the underside of the leaves. Uredinium can repeatedly infect the herbaceous host.

　　[Pathogen and Disease Development] The pathogen is *CrOnartium flaccidnm*. *CrOnartium flaccidnm* is a metaphyte; its primary hosts are peonies and pine trees, while its herbaceous hosts include peonies and impatiens. On pine trees, the rust produces sexual spores and aerospores from April to June. The aerospores are spread by wind and rain to herbaceous plants, which are then infected. Urediospores can repeatedly infect herbaceous hosts. Later in the growth cycle, teliospores are produced, which germinate to produce basidiospores. These basidiospores infect pine trees and overwinter on them.

　　【Prevention and Control Methods】① Strengthen cultivation management; plants should be planted in high-lying, well-drained areas. ② Remove diseased plants and plant debris from the herbaceous host plant in late autumn. ③ During the disease outbreak, spray with an 800-fold dilution of 15% carbendazim.

2. Brown spot disease in peony

　Brown spot disease is one of the common leaf diseases of peonies, and it occurs in all peony cultivation areas.

[Symptoms] The diseased leaves initially develop round spots of varying sizes on the leaf surface. These spots are brown and have concentric rings. Later, black mold appears on the spots, and adjacent spots merge to form large, irregular spots. In severe cases, the leaves wither and die.

[Pathogen and Disease Development] The pathogens are Cercospora paeoniae and C. variicolor. The fungi overwinter on diseased plant debris such as dead branches and fallen leaves. They spread the following year by wind and rain, with the peak incidence of disease occurring from July to September.

【Prevention and Control Methods】① In autumn, sweep up dead branches and fallen leaves and burn them to reduce sources of infection. ② During the disease period, spray with 80% zineb 700 dilution or 80% mancozeb wettable powder 600 times dilution, once every 10 days.

　　3. Bauhinia purpurea twig blight

　　[Symptoms] Infected plants first show yellowing and leaf drop at the tips of branches. In a clump of seedlings, one or two branches will turn yellow first, and then the entire plant will turn yellow and die. The surface of the xylem under the bark of the stem of infected plants has yellowish-brown longitudinal stripes, and when cut crosswise, there are yellowish-brown ring-shaped necrotic spots between the pith and the cortex.

　　[Pathogen and Disease Development] The pathogen is a Fusarium sp. which overwinters on diseased plant debris and in the soil. In June and July of the following year, the pathogen invades through the roots and spreads upwards along the vascular bundles of the roots and stems, reaching the top of the tree. The pathogen can damage the plant's vascular tissue, causing the leaves to wither and fall off.

　　4. Rose powdery mildew

　　[Symptoms] Infected plants have pale gray young leaves that become twisted and covered with a layer of white powder. In severe cases, the leaves wither, the flowers become small and few, or the plants may not even bloom. The pathogen can also infect the flower stalks, stems and other parts.

　　[Pathogen and Disease Development] The pathogen is *Sphaerotheca pannosa*. The fungus overwinters as mycelium on diseased buds, leaves, or branches. The disease is closely related to temperature; the peak incidence occurs when temperatures are between 17-25℃, specifically in April-May and September-October.

　　【Prevention and Control Methods】① Improve rose growing conditions. Ensure proper ventilation and light penetration, reduce nitrogen fertilizer application, and increase phosphorus and potassium fertilizer application. ② After winter pruning, spray with 1.02 kg/L lime sulfur solution to kill overwintering pathogens. Before disease onset, spray with a 200-fold dilution of Bordeaux mixture for prevention. When disease occurs, spray with a 1000-fold dilution of 15% carbendazim wettable powder or a 1000-fold dilution of 70% thiophanate-methyl wettable powder.

　　5. Bauhinia leaf spot disease

　　[Symptoms] This disease mainly affects the leaves, causing polygonal, yellowish-brown lesions. As the lesions expand, they merge into larger spots. In severe cases, the leaves are covered with lesions, leading to leaf death and leaf drop.

　　[Pathogen and Disease Development] The pathogen is a fungus of the genus *Cercospora* (chionea). This disease generally occurs from July to September, typically affecting the lower leaves first and then spreading upwards. Poor plant growth and severe disease during rainy seasons exacerbate the condition. The pathogen overwinters on diseased plant debris.

　　【Prevention and Control Methods】① In autumn, remove diseased fallen leaves and burn them to reduce the source of infection for the following year. ② When the disease occurs, spray with 50% carbendazim wettable powder at a dilution of 700-1000 times or 70% mancozeb wettable powder at a dilution of 800-1000 times. Spray once every 10 days, and continuous spraying for 3-4 times will have a good control effect.

　　6. Calendula powdery mildew

　　[Symptoms] The pathogen can infect leaves and stems. Infected leaves develop powdery, circular lesions with a diameter of 0.5-1.2 mm, which are irregularly distributed and eventually spread to the entire plant, covering the leaf surface with a layer of white powder. The stems are also white. In severe cases, the stems and leaves of the plant turn yellow and soon wither and die.

　　[Pathogen and Disease Development] The pathogen is Erysiphe cichoracearum. The fungus overwinters as cleistothecia or hyphae in the diseased tissues of infected leaves and stems. The pathogen is mainly spread by wind and rain. The disease is severe when the temperature is 17-25℃ and the climate is dry.

　　【Prevention and Control Methods】① Remove diseased plants immediately upon discovery to reduce the source of infection. ② Spray with a 1000-1200 times dilution of 15% wettable powder of carbendazim, or a 1000 times dilution of 70% wettable powder of methyl thiophanate, or a 100-200 times dilution of 20% antimycin.

　　7. Cherry blossom brown spot perforation disease

　Cherry blossom brown spot and perforation disease is an important disease of cherry blossom leaves, which occurs in all cherry blossom planting areas in my country.

　　[Symptoms] The disease mainly occurs on old leaves, but also infects young shoots. Initially, small purplish-brown spots appear on infected leaves, which soon expand into concentric ring-shaped circular spots about 5 mm in diameter. The edges of the spots are almost black and easily develop abscission layers. Later, brown mold appears on both sides of the diseased leaves. The center of the spots dries up and falls off, forming small circular holes. When several spots overlap, the perforations are irregular.

　　[Pathogen and Disease Development] The pathogen is *Cercospora circumscissa*, a fungus. The fungus overwinters in diseased tissues of fallen leaves and twigs. Ascospores mature in spring and are spread by wind and rain the following year when temperatures are suitable. Disease typically begins in June, with peak incidence in August and September. Frequent wind and rain exacerbate the disease. Poor tree growth can also worsen the disease. Besides cherry blossoms, this disease can also affect peach, plum, apricot, and elm-leaf plum trees.

　　[Prevention and Control Methods] ① Strengthen cultivation management, create good ventilation and light conditions, and apply more phosphorus and potassium fertilizers to enhance disease resistance. ② Remove diseased fallen leaves in autumn and prune diseased branches to reduce the source of infection for the following year. ③ Spray with 1.02-1.04 kg/L lime sulfur mixture before leaf expansion. During the disease period, spray with 1500 times dilution of 50% benomyl wettable powder, 600 times dilution of 65% zineb, or 1000 times dilution of 50% carbendazim. All of these have good control effects.

　　8. Rust disease of Chaenomeles speciosa

　　[Symptoms] In the early stage of infection, small yellow-green spots appear on the upper surface of the leaves, which gradually enlarge and turn into orange-yellow spots. In mid-June, slightly concentric black spots, i.e., sexual spores, appear on the lesions. Later, yellow powdery substances, i.e., rust spores, appear on the underside of the leaves, which produce rust spores. The disease damages pine and cypress trees in autumn and winter.

　　[Pathogen and Disease Development] The pathogen is *Gymnosporangium yamadai*. The fungus overwinters on pine and cypress trees. Teliospores are formed in late March, and microspores are produced in April after rain. These microspores are spread by wind and rain, infecting crabapple trees. In July, aerospores are produced and spread by wind to pine and cypress trees, invading young shoots. Abundant rainfall is the main condition for the occurrence of this disease.

　　【Prevention and Control Methods】① Avoid planting crabapple and pine trees together. ② In late March, when the teliospores mature, spray the pine trees with a 1:2:100 Bordeaux mixture. ③ At the initial stage of crabapple disease, spray with a 15% wettable powder of carbendazim at a dilution of 1:1500.

　　9. Rose twig blight

　　[Symptoms] It usually occurs on branches and trunks. The lesions are initially small red spots, which gradually enlarge and turn dark. The center of the lesion turns light brown. The brown and purple edges around the lesion contrast sharply with the green of the stem. The conidiophores of the pathogen appear when the center of the lesion turns brown. As the conidiophores enlarge, longitudinal cracks appear on the stem epidermis. When the disease is severe, the branches and leaves above the diseased part wither and die.

　　[Pathogen and Disease Development] The pathogen is *Coniotnyriilln f. Uckelii*. The fungus overwinters as mycelial spores on diseased branches. The following year, conidia are produced and spread by wind and rain. The pathogen usually enters through wounds, and grafting and pruning cuts are easily infected.

　　[Prevention and Control Methods] ① Collect and burn diseased and dead branches in late autumn. ② Pruning should be done on sunny days. ③ When the disease occurs, spray with 50% thiophanate-methyl wettable powder, 70% chlorothalonil wettable powder, or 50% carbendazim wettable powder at a dilution of 1000 times for prevention and control.

　　10. Rose black spot disease

　　Rose black spot disease is a global disease that causes great damage. The pathogen damages the leaves, causing a large number of leaves to fall off, resulting in poor plant growth.

　　[Symptoms] After the leaves are infected, circular purplish-black spots or irregular spots appear on the leaf surface. The edges of the spots are reddish-brown or purplish-brown and radiate outwards. Gradually, the spots merge together to form large spots, and a large area of ​​the surrounding leaf tissue turns yellow. Diseased leaves easily fall off, and in severe cases, all the lower leaves of the entire plant fall off, leaving it bare and dry.

　　[Pathogen and Disease Development] The pathogen belongs to the genus *Diplocarpon rosac*. ​​The black spot fungus overwinters as mycelium or conidiophores on diseased plant debris. It spreads via rainwater or splashing from irrigation water, and can also be spread by insects. The disease is most severe in warm, humid environments, especially during rainy seasons. Newly transplanted plants, with damaged root systems and weakened growth, are particularly susceptible. Generally, light-colored flowers, small flowers, and upright varieties are more prone to infection.

　　【Prevention and Control Methods】① Promptly remove withered leaves and branches, and burn them to reduce the source of infection. ② Strengthen cultivation management, apply more phosphorus and potassium fertilizers to improve the plant's disease resistance. ③ Spray early with 50% carbendazim wettable powder at a dilution of 1:1000, or 50% mancozeb at a dilution of 1:1000, or 70% thiophanate-methyl wettable powder at a dilution of 1:1000, or Bordeaux mixture (1:1:200).

　　11. Powdery mildew of roses

　 Powdery mildew is a global disease affecting roses, occurring throughout my country. It is highly damaging to roses, causing premature leaf drop, deformed flower buds, or complete failure to open when severe. The disease is more severe in greenhouses than in open fields.

　　[Symptoms] The disease affects leaves, young shoots, and flowers. A prominent characteristic is the appearance of a white powdery substance on infected areas. During the growing season, small white powdery spots appear on infected leaves, gradually expanding into round or irregularly shaped patches. In severe cases, these spots merge into larger areas. Older leaves are more resistant. The powdery layer on petioles, bark, and thorns is thick and difficult to peel off. When flower buds are infected, their surface is covered with a white powder, resulting in deformed flowers.

　　[Pathogen and Disease Development] The pathogen is *Sphaerotheca pannosa*, belonging to the Ascomycota. Its asexual stage is *Oidium leucoconium*. The pathogen overwinters as mycelium in buds. The following year, the pathogen becomes active as buds sprout, infecting tender parts and producing new fungal vesicles, which are then spread by wind and other means. In open-field cultivated roses, the disease is most prevalent in spring (May-June) and autumn (September-October). In northern regions, it mainly affects roses in spring, while in greenhouse cultivation, it can occur year-round. Powdery mildew can occur when the room temperature is above 2-5℃. Lower nighttime temperatures (15-16℃) and higher humidity (90%-99%) favor spore germination and invasion, while higher daytime temperatures (23-27℃) and lower humidity (40%-70%) favor spore formation and release. There are also differences in disease resistance among varieties. Small-leaved, hairless, creeping, multi-flowered varieties are more resistant to disease; most aromatic varieties, especially red varieties, are susceptible to disease.

　　【Prevention and Control Methods】① Improve planting conditions: Ensure greenhouse ventilation and light penetration, reduce humidity, avoid excessive nitrogen fertilizer application, and apply more phosphorus and potassium fertilizer appropriately. ② Prune diseased branches, buds, and leaves to reduce sources of infection. ③ Spraying with 15% wettable powder of carbendazim at a dilution of 1:1000 or 70% wettable powder of thiophanate-methyl at a dilution of 1:1000 in the early stages of disease has good control effects. Alternatively, spray with 1 kg/L lime sulfur mixture.

　　12. Anthracnose of Magnolia denudata

　　[Symptoms] This disease mainly affects the leaves. In the early stages, small chlorotic spots appear on the leaf surface and gradually enlarge, forming round or irregular lesions with dark brown edges and a lighter center. Small black dots appear on the lesions. If the lesions occur at the leaf margin, the leaves will become slightly distorted. In severe cases, the lesions merge to form large lesions, causing the entire leaf to wither, scorch, and fall off.

　　[Pathogen and Disease Development] The pathogen is *Colletotricus gloesporioides*. The bacteria overwinter in diseased plant debris and spread via wind and rain in June and July of the following year. Disease outbreaks occur when there is abundant rainfall, humid air, and poor ventilation, with the peak incidence occurring from July to September. Young *Magnolia grandiflora* trees are more severely affected.

　　【Prevention and Control Methods】① Plants should not be planted too close together to ensure ventilation and light penetration. Promptly prune and destroy diseased branches and leaves to reduce the source of infection. ② In the early stages of the disease, spray with 70% carbendazim at a dilution of 500 times, or 65% zineb wettable powder at a dilution of 800 times, or Bordeaux mixture at a ratio of 1:1:200, once every 10 days. Three consecutive sprays are recommended for best results.

　　13. Bacterial leaf spot of peach

　Bacterial leaf spot of peach occurs throughout the country and is one of the main causes of premature leaf drop in peaches.

　　[Symptoms] In the early stages, infected leaves develop round or polygonal brown, water-soaked lesions surrounded by a pale yellow halo. Absorption layers easily form at the edges, leading to perforation. When lesions merge, the perforations become irregular in shape, and the affected leaves fall off prematurely. On infected fruit, small, oily brown spots appear, and the lesions enlarge, eventually becoming sunken and cracked. On diseased branches, water-soaked purplish-brown spots appear centered on lenticels, later becoming sunken and cracked.

　　[Pathogen and Disease Development] The pathogen is *Xanthomonas pruni*. The fungus overwinters on old lesions and begins to infect new leaves and shoots in May. The disease is exacerbated in humid weather.

　　【Prevention and Control Methods】① Remove diseased fallen leaves and dead branches in winter, strengthen water and fertilizer management, and pay attention to ventilation and light penetration. ② Spray with Bordeaux mixture at a ratio of 1:1:120 before bud break, once every 10 days, for a total of 3-4 sprays.

　　14. Peach gummosis

　　[Symptoms] Occurs on the main trunk and branches, oozing a gum-like substance, causing leaves to turn yellow, weaken growth, and even die.

[Pathogen] Various factors can cause peach gummosis, such as physiological disorders, bacterial parasites, and damage (including frost fertilization). ② Timely prevention and control of common peach diseases and pests.

　　15. Oleander black spot disease

　　[Symptoms] Lesions occur on the edges or middle of the leaves, appearing as semicircles or circles. When several lesions merge, they form a wavy pattern. Lesions can appear on both the upper and lower surfaces, with the upper surface being slightly darker than the lower surface. The lesions are grayish-white or grayish-brown. In later stages, a black powdery mold layer appears on the affected area, generally occurring on older leaves.

　　[Pathogen and Disease Development] The pathogen is a fungus of the genus *Alternaria*. Spores are spread by wind and rain; excessive rainfall easily causes this disease. The disease is most common on older leaves, lower leaves, and suckers sprouting from the roots.

　　【Prevention and Control Methods】① Strengthen management and improve plant ventilation and light penetration. Apply more phosphorus and potassium fertilizers to enhance tree vigor. ② Spray with 75% chlorothalonil at a dilution of 800 times for prevention and control.

　　16. Rose rust

　　[Symptoms] This disease can infect rose buds, leaves, receptacles, and young branches. In spring, infected buds turn pale yellow, swell, and gradually wither and die. In autumn, a few infected axillary buds may grow leaves, but they will die in winter. Infected leaves show irregular light yellow lesions on the upper surface and black blisters on the underside, causing premature leaf drop.

　　[Pathogen and Disease Development] The pathogen is *Phragmidlium rose-rugosae*. The fungus overwinters as mycelium within buds and is the primary source of infection for the following year. This fungus is a monotrophic parasite. Resistance varies among different rose varieties; Bulgarian red rose, white rose, and the former Soviet Union perfume rose are relatively resistant. The optimal temperature for disease development is 24-26℃, and abundant rainfall is the dominant factor in disease spread.

【Prevention and Control Methods】① Promptly remove and burn dead branches and leaves to reduce the source of infection. ② Generally, spray pesticides before the peak disease period in late June and mid-August, once every 8-10 days, for 2-3 consecutive times. Suitable pesticides include 75% chlorothalonil at 800 times dilution, 50% mancozeb at 800-1000 times dilution, and 50% thiophanate-methyl at 500 times dilution.

　　17. Amaryllis erythroplasia

　　[Symptoms] Leaves, flower stalks, bracts, and bulbs can all be infected with this disease. In the early stages, irregular reddish-brown spots appear on the leaves. Later, these spots enlarge into oval or spindle-shaped, sunken purplish-brown lesions, which may merge, causing the leaves to deform and die. Small reddish-brown spots also appear on the flower stalks, which rapidly expand into reddish-brown streaks, causing the stalks to bend towards the affected side. When bulbs are infected, circular or oval lesions form, and in humid environments, a layer of granular, dark brown mold may appear.

　　[Pathogen and Disease Development] The pathogen is *Stagonospora curtisii*. The fungus overwinters as conidiophores on diseased plant debris. Planting diseased bulbs will become a source of infection for the following year. The conidia of the fungus are spread by wind and rain. Cross-infection can occur when *Daffodils* are the preceding crop, or when planted adjacent to plants such as *Crinum asiaticum*.

【Prevention and Control Methods】① Avoid continuous cropping and select disease-free bulbs for planting. Before planting, remove affected scales and avoid planting too densely. Remove diseased plants and leaves promptly. ② When the disease occurs, spray with 75% chlorothalonil wettable powder at a dilution of 700 times or 80% zineb at a dilution of 500-700 times to prevent the spread of the disease.

　　18. Gladiolus virus disease

　Donut virus disease is a global disease that occurs in all areas where donuts are grown. It primarily causes bulb degeneration, stunted growth, short flower spikes, and fewer, smaller flowers, severely impacting the quality of cut flowers.

　[Symptoms] This disease mainly infects leaves and flowers. Initially, infected leaves develop chlorotic circular spots, which expand into polygonal shapes due to the restriction of leaf veins, eventually turning brown. Diseased leaves exhibit a mixture of dark and light green; in severe cases, they yellow and become distorted. Affected plants are stunted, with short flower spikes, fewer flowers, and smaller flowers. In some varieties, the petals discolor, appearing fragmented and patchy.

　　[Pathogens and Disease Development] The pathogens are Bean Yellow MosaiC virus and Cucumber MosaiV. Both viruses overwinter in diseased bulbs and plant debris. They are transmitted through sap and various aphids. Both viruses have a wide host range, with many vegetables and weeds serving as source plants.

　　【Prevention and Control Methods】① Strengthen quarantine and promptly destroy infected bulbs. ② Establish a seed-producing base for disease-free bulbs if conditions permit. ③ Remove diseased plants from the field and weeds near the planting area to reduce sources of infection. ④ Spray insecticides to control aphids and eliminate vectors that transmit the virus.

　　19. Gladiolus streak disease

　　[Symptoms] The diseased plant initially develops chlorotic spots on the leaves. The spots are surrounded by leaf veins and are polygonal. The plant becomes shorter, the leaves are wrinkled and twisted, and the flowers become smaller. On pink varieties, the petals are fragmented.

　　[Pathogen and Disease Development] The pathogen is bean yellow mosaic virus. The virus overwinters in diseased bulbs and within diseased plants, becoming the primary source of infection for the following year. The virus is transmitted through sap and aphids, and its widespread spread is also facilitated by using infected bulbs as propagation material. The virus enters through micro-wounds.

　　【Prevention and Control Methods】① Strengthen quarantine measures; any imported bulbs found to contain viruses should be destroyed immediately. ② Establish virus-free, high-quality bulb breeding bases. ③ Control pests and diseases; use 40% dimethoate at a dilution of 2000 times to control aphids, and promptly remove diseased plants from the field to prevent cross-infection. ④ Select more disease-resistant varieties for cultivation.

　　20. Cycad spot disease

　　[Symptoms] After infection, small, nearly circular or irregular lesions appear on the leaflets of the cycad. The center of the lesion is dark brown to grayish-white, while the periphery is reddish-brown. The lesions gradually enlarge and connect to form a section, at which point the leaf tissue above the lesion soon withers and dies.

　　[Pathogen and Disease Development] The pathogen is *Pestalotia cycadis*. The pathogen overwinters on diseased leaves and spreads through conidia the following year. The disease is severe during hot, rainy seasons and under poor cultivation conditions. Cycads damaged by frost in winter are also susceptible to this disease.

　　【Prevention and Control Methods】①The main prevention and control measure is to prune diseased and withered leaves or leaf segments. ②At the early stage of the disease, spray with 75% chlorothalonil wettable powder at a dilution of 600 times, or Bordeaux mixture at a dilution of 1:1:200, or 50% thiophanate-methyl wettable powder at a dilution of 800-1000 times.

21. Gladiolus wilt disease

　　[Symptoms] This disease mainly occurs in the field. Infected plants exhibit bent and wrinkled petioles in young leaves, yellowing and drying of leaf clusters, and bent, darker-colored flower stalks that eventually yellow and wither. When the bulbs are infected, some develop small, irregular, nearly circular, water-soaked lesions. These lesions gradually turn reddish-brown to dark brown, becoming sunken and ring-shaped. In severe cases, the entire bulb becomes blackish-brown and rotten. When the bulbs are severely infected, the seedlings are weak or die quickly. Mildly infected bulbs may grow to a normal size, but later the leaf tips will yellow and the plant will gradually die downwards.

　　[Pathogen and Disease Development] The pathogen is *Fusarium oxysporum* var. *gladidid*. The pathogen overwinters in diseased bulbs and soil, entering through wounds; it is a seed-borne and soil-borne disease. Continuous cropping or planting with diseased bulbs easily exacerbates the disease.

　　【Prevention and Control Methods】① Adopting a 2-3 year crop rotation can control the disease. ② When diseased plants are found in the field, the diseased plants and the soil around their roots should be removed. ③ Before planting, soak the bulbs in a 50% carbendazim solution (500 times dilution) for half an hour, then mix with 50% thiram before planting.

　　22. Sunburn in Clivia

　　【Symptoms】Indistinct, yellowish, and dry patches appear on the edges of infected leaves. 【Pathogen and Disease Cycle】Clivia sunscald is a physiological injury to Clivia plants. It often occurs during the hot summer months, especially in the seedling stage when the leaves are tender and under strong sunlight.

　　【Prevention and Control Methods】① When growing Clivia in a greenhouse, provide appropriate shade from June to September. When the indoor temperature exceeds 30°C, increase ventilation or spray water to cool it down. ② Place it in a cool, well-ventilated area. ③ Once Clivia develops sunscald, prune the affected leaves to prevent the damage from spreading and causing other diseases.

　　23. Clivia leaf spot disease

　　[Symptoms] This disease mainly infects the leaves. In the early stages, small brown spots appear on the leaves, gradually expanding into large, irregularly shaped lesions that are yellowish-brown to grayish-brown. The affected area is slightly sunken with slightly raised edges. In later stages, the lesions dry out, and small black dots appear on the surface.

　　[Pathogen and Disease Development] The pathogen is a fungus. This disease is more likely to occur when excessive nitrogen fertilizer is applied and relatively insufficient phosphorus and potassium fertilizer is used in cultivation. Leaf spot disease is also prone to occur under hot and dry conditions, or when scale insect infestation is severe.

　　【Control Methods】① Remove diseased leaves and plant debris to reduce the source of infection. ② Control scale insects to prevent pest infestation and reduce infection. ③ At the initial stage of disease, spray with 50% carbendazim at a dilution of 1000 times, 70% thiophanate-methyl wettable powder at a dilution of 1000 times, or 50% mancozeb at a dilution of 1000 times.

　　 24. Wilt disease of Albizia julibrissin

　　[Symptoms] This disease is devastating to Albizia julibrissin and can spread rapidly. Infected plants exhibit drooping, wilting leaves that turn pale green or pale yellow. Later, the leaves fall off, and the branches begin to die. Examination of the sapwood reveals clearly browned affected areas. Even before the leaves wither, numerous conidia of the pathogen are produced in the lenticels of the diseased plant. These conidia are spread by wind and rain.

　　[Pathogen] The pathogen is Fusarium oxysporwm schl.f.sp.pernciosium.

　　【Prevention and Control Methods】① Select disease-resistant varieties for cultivation, such as Charlotte with deep red flowers and Tryon with light-colored flowers. ② Cut down and burn any dead plants and severely infected plants to prevent the spread of the disease.

　　25. Chrysanthemum black spot disease

　　Chrysanthemum black spot disease, also known as brown spot disease or leaf spot disease, is a serious disease of chrysanthemums that occurs throughout the country.

　　[Symptoms] Initially, infected leaves develop round, oval, or irregularly shaped purplish-brown spots of varying sizes, which later turn dark brown or black, with a diameter of 2-10 mm. The boundary between infected and healthy parts is clear. In later stages, the center of the spots lightens to grayish-white and develops small black dots. In severe cases, only the top 2-3 leaves are unaffected. The diseased leaves wither prematurely but do not immediately fall off, remaining attached to the plant.

　　[Pathogen and Disease Development] The pathogen is *Septoria Chrysanthemella*. The fungus overwinters as mycelium and conidiophores on diseased plant debris, becoming the source of infection for the following year. The conidiophores release numerous conidia, which are spread by wind and rain. Heavy autumn rainfall, high planting density, and poor ventilation all favor disease development. There are differences in disease resistance among varieties; for example, *Zihe* and *Yuanyang* are relatively resistant, while *Guangdong Huang* is most susceptible. Plants propagated by root division are more severely affected, while cuttings taken from the upper part of healthy plants are less susceptible.

　　【Prevention and Control Methods】① For small-scale planting, manually remove diseased leaves and burn them. ② Improve the planting environment. In areas with severe disease, implement crop rotation, avoid overly dense planting to ensure ventilation and light penetration, and promptly drain excess water. ③ During the disease period, spray with 100-150 times Bordeaux mixture or 500 times dilution of 80% dichlorvos wettable powder. Alternatively, spray with a mixture of 1000 times dilution of 50% thiophanate-methyl and 500 times dilution of 80% dichlorvos, or a 1000 times dilution of a mixture of 45% chlorothalonil and carbendazim suspension. These methods are more effective than using a single agent.

　　26. Sooty mold of Lagerstroemia indica

　　[Symptoms] The disease first appears on the upper surface of the leaf along the midrib, gradually covering the entire leaf surface. In severe cases, the leaf surface is covered with black, sooty material. The mycelium of the pathogen covers the leaf surface, blocking the stomata and hindering normal photosynthesis.

　　[Pathogen and Disease Development] Crape myrtle sooty mold (Capnodium sp.) is a species of Capnodium, belonging to the class Rhizoctonia in the subphylum Ascomycota. The pathogen overwinters as mycelium or ascocarps on the leaves or branches. Spring and autumn are the peak seasons for the disease. Excessive shade and dampness increase susceptibility. The pathogen is spread by scale insects and aphids via wind and rain. The nectar secreted by aphids on crape myrtle provides a nutrient source for the pathogen's growth.

　　【Prevention and Control Methods】① Strengthen cultivation management, ensure appropriate planting density, and prune diseased and excess branches in a timely manner to improve ventilation and light penetration. ② Control of sooty mold should focus on insect control. Spray with 10-20 times diluted pine resin mixture and 1500-2000 times diluted 50% phosmet emulsion to kill scale insects (spraying at the initial hatching stage of larvae is more effective). Alternatively, spray with 2000 times diluted 40% dimethoate or 1000 times diluted 50% malathion to kill aphids. Lime sulfur mixture at 1.01 kg/L also has good bactericidal effect.

　　27. Strobilanthelasma gondii virus disease

Salvia splendens virus disease, also known as salvia splendens mosaic virus, is the most common disease of salvia splendens and occurs throughout the country.

　　[Symptoms] After the plant is infected, the leaves mainly show mottled leaves with alternating shades of green and yellow-green. In severe cases, the leaf surface becomes uneven and may even show fern-like symptoms. The number of flowers decreases sharply and the plant becomes stunted.

　　[Pathogens and Disease Development] The pathogens are cucumber mosaic virus (CMV), tobacco mosaic virus (TMV), Salvia virus 1, beet scab virus, and broad bean wilt virus. Cucumber mosaic virus has a wide host range and can be transmitted by various aphids. In Beijing, Shanghai, and other cities, the growing season of Salvia splendens coincides with the peak breeding season of aphids, and there is a strong correlation between aphids and disease occurrence.

　　【Prevention and Control Methods】① Insecticides and disease control are important measures to control the occurrence and spread of this disease. Apply insecticides to control aphids. ② Remove CMV hosts near the Salvia splendens planting area to reduce sources of infection. ③ Select virus-free and healthy mother plants for seed production.

　　28. Powdery mildew of Impatiens flowers

　　[Symptoms] This disease primarily affects leaves, but can also spread to young stems, flowers, and fruits. Initially, infected leaves develop scattered, irregular white powdery patches on their surface. As the disease progresses, the leaf surface gradually becomes covered with a white powdery layer. In early autumn, small yellow dots form within the powdery layer, gradually darkening to a blackish-brown. In later stages, diseased leaves turn yellow and become twisted.

　　[Pathogen and Disease Development] The pathogen is *Sphaerotheca fuliginea*. The fungus overwinters in diseased plant debris and seeds of impatiens, releasing ascospores for primary infection during the following year's disease outbreak. Subsequent conidia are produced for secondary infections. The disease is spread by wind and rain. The peak disease period is August and September, when high temperatures, high humidity, and dense planting exacerbate the disease. Poor ventilation also worsens the disease.

　　【Prevention and Control Methods】① Strengthen cultivation management, ensure appropriate planting density, adequate ventilation and light penetration, apply more phosphorus and potassium fertilizers, and avoid excessive nitrogen fertilizer application. ② Promptly remove diseased plants and leaves and burn them to reduce the source of infection for the following year. ③ During the disease period, spray with 25% wettable powder of carbendazim at a dilution of 2000-3000 times, or 70% wettable powder of thiophanate-methyl at a dilution of 1000-1200 times, or 25% wettable powder of carbendazim at a dilution of 500 times.

　　29. Daylily withering disease

　　[Symptoms] The diseased leaves initially show yellowish-brown to grayish-brown spots that turn pale green at the leaf tip or leaf margin. Many small black dots appear on the diseased area. When the disease is severe, the spots merge to form large lesions, causing the entire leaf to wither and die.

　　[Pathogen and Disease Development] The pathogens are fungi of the genus *Amanita* and the genus *Anthracnose*. The fungi mainly overwinter on diseased plant debris and are spread by wind and rain. Disease outbreaks occur in May and June of the following year, with severe outbreaks in August. Poor ventilation and drainage favor the development of this disease.

　　【Prevention and Control Methods】① Promptly remove and destroy diseased plant debris to reduce sources of infection. ③ In the early stages of the disease, spray with a 600-fold dilution of 50% zineb wettable powder or an 800-fold dilution of 50% thiophanate-methyl wettable powder. Alternatively, spray with 1% Bordeaux mixture.

　　30. Narcissus brown spot disease

　　Large brown spot disease of daffodils is a global disease, and it is prevalent in daffodil cultivation areas in my country. Infected plants may experience partial leaf withering in mild cases, while in severe cases, the above-ground parts wither and die 4-6 weeks before the bulbs mature, severely reducing the maturity of the bulbs.

　　[Symptoms] In the early stages of the disease, lesions appear at the tips of leaves, are brown, and have a clear boundary with healthy parts. Later, lesions will also appear on the edges and middle of the leaves, and flower stalks can also be infected. The lesions are initially brown spots, expanding into oval or irregular shapes. Individual lesions can reach 1 cm x 4.5 cm in size. Lesions merge to form long, thin streaks, with the upper and lower edges turning yellow rapidly. When lesions occur at the edges, leaf growth stagnates and the leaves become twisted. On Chinese daffodils, the lesions are noticeably thicker, and the surrounding tissue turns yellow. On trumpet daffodils, the lesions are brown, but the surrounding tissue does not turn yellow.

　　[Pathogen and Disease Development] The pathogen is *Stagonospora curtisii*, a fungus that causes brown spotting in daffodils. The fungus overwinters or oversummers as mycelium or conidia on the upper part of the bulb epidermis or on dead leaves. Conidia are spread by wind and rain. The fungus can also oversummer on other hosts such as amaryllis and spider lilies. In southern regions, the disease is more severe during the rainy season in April and May. Overcrowding, poor drainage, and continuous cropping all exacerbate the disease. There are also differences in disease resistance among varieties. *Daffodils 'Mandarin Daffodils'* are more severely affected, while *Daffodils 'Green'* and *Daffodils 'Trumpet'* are less susceptible.

　　【Prevention and Control Methods】①Prune diseased leaves and remove diseased plants to reduce the source of infection. ②Avoid continuous cropping or planting amaryllis, spider lilies, agapanthus, or other similar plants near daffodil planting sites. ③Avoid wounds when harvesting bulbs. Before planting, remove the membranous scales and soak the bulbs in a 1% formaldehyde solution for 0.5-1.0 hours, or a 50% carbendazim solution at 500x dilution for 12 hours, or a 0.1% mercuric chloride solution for 0.5-1.0 hours to reduce initial infection. ④During the disease period, spray with 1% Bordeaux mixture, 75% chlorothalonil at 500x dilution, or 70% thiophanate-methyl at 1000x dilution.

　 　31. Peony erythroplasia

Peony red spot disease, also known as peony brown spot disease, is the most common and important disease in cultivated peonies, occurring throughout my country. Red spot disease causes premature withering of peony leaves; repeated occurrences can weaken the plant's growth, resulting in stunted growth, fewer and smaller flowers, and even plant death.

　　[Symptoms] This disease primarily affects leaves, but can also infect branches, flowers, and fruit shells. Initially, infected leaves develop small, green, pinhead-sized dots on the underside, which later expand into nearly circular, purplish-brown spots, 4-25 mm in diameter. The upper surface of the leaves shows indistinct light brown concentric rings on the lesions. Lesions often merge, leading to complete leaf scorching and breakage in severe cases. In humid conditions, a dark green mold layer appears on the underside of the affected areas. When the disease infects the stem, small, oblong, purplish-brown spots appear, some raised. These spots expand slowly, are 3-5 mm long, crack in the center and sink in; in severe cases, they may merge into larger patches. Symptoms on infected petioles are the same as on green stems. Lesions on sepals and petals appear as small, purplish-red spots.

　　[Pathogen and Disease Development] The pathogen is *Cladosporiwm paeoniae*, belonging to the genus *Cladosporiwm* of the order Cladosporiales in the class Hyphomycetes of the subphylum Deuteromycetes. The pathogen mainly overwinters as mycelium on diseased leaves, branches, fruit shells, and other plant debris. The following spring, conidia are produced and infect the plant. The lower leaves are the first to be infected. The pathogen rarely reinfects; the severity of the initial infection determines the severity of the disease. In the Beijing area, the disease begins to appear in April-May, with peak incidence in July-August. Different varieties exhibit varying resistance; for example, varieties such as *Donghai Chaoyang*, *Xiao Ziling*, *Lanpan Yinju*, and *Fengluo Jinchi* are highly resistant, while varieties such as *Zi Furong*, *Yanzhi Dianyu*, and *Wawa Mian* are susceptible. [Control Methods] ① Reduce the source of infection: In autumn, cut off the above-ground parts of the branches and leaves at ground level, taking care not to damage the buds in the soil, and burn the diseased plant debris. ② Strengthen cultivation management to control the occurrence of the disease. Planting density should be reasonable to facilitate ventilation and light penetration. Overly large plants should be transplanted promptly. ③ After the peony leaves unfold but before flowering, spray with a 1000-fold dilution of 50% carbendazim wettable powder. After flowering, alternately spray with a 500-fold dilution of 65% zineb wettable powder and 1% Bordeaux mixture, once every 7-10 days.

32. Powdery mildew of Buxus macrocarpa

　　[Symptoms] Powdery mildew is mostly distributed on the upper surface of large-leaved boxwood leaves, but can also grow on the lower surface. Individual lesions are round and white, while multiple lesions merge irregularly. When the white powdery layer is wiped away, yellow circular spots appear at the affected site. In severe cases, diseased leaves become wrinkled, and diseased shoots become twisted and deformed.

　　[Pathogen and Disease Development] The pathogen is *Oidium euonymi-japonicae*. The pathogen overwinters as mycelium and conidia on fallen leaves and is spread by wind and rain. Overcrowded planting and failure to prune in a timely manner exacerbate the disease.

　　[Prevention and Control Methods] ① Remove and burn diseased leaves and plant debris. ② When propagating by cuttings, do not overcrowd the cuttings. ③ When the disease occurs, spray with 800-1500 times diluted solutions of carbendazim, thiophanate-methyl, or thiophanate-methyl, or 1 kg/L lime sulfur solution, all of which have good control effects.

　　33. Leaf spot disease of wintersweet

　　[Symptoms] The diseased leaves initially have small, light green, water-soaked round spots on the leaf surface. As the spots expand, they develop into round or irregular brown spots. In the later stages, small black dots appear in the center of the spots.

　　[Pathogen and Disease Development] The pathogen is a fungus belonging to the genus *Phyllosticta calycanthi*. The fungus overwinters on diseased plant debris and fallen leaves. It spreads via wind and rain. The disease is more severe in humid climates.

　　【Prevention and Control Methods】① Promptly remove diseased fallen leaves to reduce sources of infection. ② Spray with a 1000-fold dilution of 50% carbendazim when the disease occurs.

　　34. Phlox virus disease

　　[Symptoms] The infected plant and its flowers are abnormal. The flowers turn green and become deformed. The leaves turn pale green, the tissues harden, and they become brittle and easily broken. Sometimes the leaf tips and edges turn red or purple and dry out.

　　[Pathogens and Disease Development] The pathogens are Tobacco rattlle virus and Tobacco rattlle virus. The viruses are transmitted through sap, leafhoppers, and aphids.

　　【Prevention and Control Methods】① Remove diseased plants promptly. ② Use disease-free materials to propagate new plants. ③ Spray insecticides promptly to prevent aphids and leafhoppers from spreading the disease.

　　35. Dahlia virus disease

Dahlia virus disease, also known as dahlia mosaic disease, occurs in provinces and cities in my country such as Guangdong, Kunming, Shanghai, Inner Mongolia, and Liaoning. In severe cases, the plants stunt and the disease is generally found in sporadic locations.

　　[Symptoms] Dahlia leaves develop vein blemishes or yellowing of the veins and mosaic patterns, hindering leaf development. Some leaves develop characteristic ring-shaped spots. Plants infected with the virus in summer, close to flowering, may not show any symptoms initially, but mosaic patterns and dwarfing will appear the following year.

　　[Pathogen and Disease Development] The pathogen is Tomato Spotted Wilt Virus (TWV). Dahlia mosaic virus can be transmitted through sap and grafting. Leafhoppers and aphids can also transmit the virus. Under normal conditions, dahlia sap inoculation is difficult to succeed. Dahlia tubers can also carry the virus. However, dahlia seeds do not transmit the virus. Dahlia mosaic virus can also cause disease in plants such as Coreopsis grandiflora, Coreopsis pilosula, Petunia, and Zinnia elegans.

　　[Prevention and Control Methods] ① Avoid using virus-infected tubers as propagation material. Immediately remove and burn diseased plants and use seed tubers for propagation. ② Tomato spotted wilt virus does not easily reach the plant's growing point; virus-free new plants can be obtained through shoot tip tissue culture. ③ During the plant's growing season, spray insecticides to control virus-transmitting insects. Spray with 40% dimethoate at a dilution of 2000 times, or 50% malathion, 20% diazinon, or 70% propafenone at a dilution of 1000 times each.

　　36. Tulip petal disease

Tulip white streak disease, also known as tulip white streak disease, occurs in all tulip-producing regions. It is one of the important causes of tulip bulb degeneration.

　　[Symptoms] This disease primarily infects the leaves and corolla of tulips. Infected leaves develop light green or grayish-white streaks, sometimes forming a mosaic pattern. Petals become deformed, and in single-colored flowers, pale yellow or white stripes or irregular spots appear on the petals. Infected bulbs degenerate and become smaller, resulting in poor plant growth, stunted growth, and smaller, deformed flowers.

　　[Pathogen and Disease Development] The pathogen is Tulip Breaking Virus (TuBV), which overwinters in diseased bulbs, becoming the source of infection for the following year. It is transmitted non-persistently by peach aphids and other aphids. This virus can also infect lilies, causing mosaic patterns or latent symptoms. Under natural cultivation conditions, double-flowered tulips are more susceptible to the disease than single-flowered tulips.

　　【Prevention and Control Methods】①Strengthen quarantine to control the spread of the disease. Remove diseased plants immediately upon discovery. Avoid planting too close to lilies to prevent cross-infection. ②Control aphids by regularly spraying insecticides to reduce vectors.

　　37. White rust disease of morning glory

　　[Symptoms] The disease mainly affects leaves, petioles, and young stems. Initially, small light green spots appear on the leaves, gradually turning pale yellow with indistinct edges. In severe cases, these spots expand into large lesions. Later, white scar-like protrusions appear on the underside of the affected area. When these protrusions rupture, they release a white powdery substance, which is the sporangiospore of the pathogen. When young stems are affected, flowers and stems become twisted. When lesions surround petioles and young shoots, the host portion above the girdled area grows poorly, withers, and dies.

　　[Pathogen and Disease Development] The pathogen is *Albugo ipomoeae-panduranae*, a fungus belonging to the genus *Albugo*. The fungus overwinters as oospores in diseased tissues. The following spring, the oospores germinate to produce sporangia, which then invade plants in the Convolvulaceae family, such as morning glories. The peak disease period is generally from August to September. Morning glory seeds can carry the pathogen and become a source of infection for the following year.

　　【Prevention and Control Methods】① Promptly remove and destroy diseased plants to reduce seed contamination. ② Select disease-free seeds for propagation and disinfect them before sowing. Avoid crop rotation with Convolvulaceae plants. ③ Spraying with 1% Bordeaux mixture or 50% Phytophthora inoculant at a dilution of 500 times at the initial stage of disease, once every 10-15 days, has a good control effect.

　　38. Lotus brown spot disease

　　Lotus brown spot disease, also known as lotus black spot disease, is a common occurrence in lotus cultivation areas of my country.

　　[Symptoms] In the early stages of the disease, large yellowish spots appear on the lotus leaves, which are more obvious on the underside of the leaves. The spots gradually expand into irregular brown spots. In severe cases, the entire leaf, except for the veins, is covered with spots, making it look like it has been burned from a distance. In the later stages, many dark brown mold-like substances grow on the spots.

　　[Pathogen and Occurrence Pattern] The pathogen is *Alternaria nelumbii*. The fungus overwinters on diseased plant debris. During the lotus growing season, it produces conidia that are spread by wind and rain, and can repeatedly infect plants. The disease is severe when humidity is high and nitrogen fertilizer is applied. High summer temperatures and aphid-infested plants also exacerbate the disease.

　　【Prevention and Control Methods】① Thoroughly remove diseased leaves and plant debris, and destroy them to reduce the source of infection. For potted plants, replace the soil annually. ② During the disease outbreak period, spray with a 500-fold dilution of 65% zineb or an 800-fold dilution of 75% chlorothalonil to prevent the disease from spreading.

　　39. Chrysanthemum indicum collapses due to illness

　　[Symptoms] This disease mainly occurs in the seedling stage, affecting the base of the stem and roots. The affected areas are sunken and constricted, turning dark brown, causing the seedlings to collapse and die. If the stem tissue becomes lignified, the seedlings often do not collapse but instead exhibit damping-off symptoms. When soil moisture is high, a layer of white, fluffy mycelium is often visible on the diseased seedlings and the surrounding soil surface.

　　[Pathogen and Disease Development] The pathogen is Fusarium javaniCum. The fungus overwinters in the soil or on diseased plant debris. It is highly saprophytic and can survive in the soil for a long time. It is spread by irrigation water and rainwater. High soil moisture, dense sowing, and unsuitable temperature all favor the occurrence of this disease. Continuous cropping leads to more severe disease.

　　【Prevention and Control Methods】① Soil Treatment. Use 40% seed dressing agent or 40% pentachloronitrobenzene, applying 6-8 grams per square meter and mixing it thoroughly into the sowing soil. ② At the initial stage of disease, spray with a 500-fold dilution of 50% carbendazim wettable powder or a 600-fold dilution of 75% chlorothalonil wettable powder. Apply once every 7-10 days, for a total of 3 applications.

　　40. Canna mosaic virus

Canna mosaic virus is a common disease of canna lilies and is prevalent in areas where canna lilies are grown in my country.

　　[Symptoms] Mottled or yellow-green spots appear on the leaves of infected plants. The petals become smaller and variegated. When the disease is severe, the leaves become deformed and curled inward, and the spots become necrotic.

　　[Pathogen and Disease Development] Canna mosaic virus is caused by Cucumber Mosaic Virus (CMV). Transmission mainly occurs through aphids and sap contact. Resistance varies among different canna varieties. Common canna, large-flowered canna, and pink-leaved canna are severely affected, while red-flowered canna exhibits strong resistance.

【Prevention and Control Methods】① Since canna lilies are propagated by root division, viruses can easily be transmitted year after year. Therefore, when propagating, it is advisable to select virus-free mother plants as propagation material. Diseased plants should be removed and destroyed immediately to reduce the source of infection. ② This disease is transmitted by aphids. Use insecticides to control aphids and reduce the disease vector. Spray with a 2000-fold dilution of 40% dimethoate, or a 1000-fold dilution of each of 50% malathion, 20% chlorpyrifos, and 70% propafenone.