What are the control methods for sclerotium disease in hyacinths?
[Symptoms] It affects leaves and bulbs and is a common disease of hyacinths. Infected plants are stunted and slow to develop. The leaves of diseased plants are grayish yellow; as the disease progresses, the leaves gradually wither and detach very easily from the bulb; the interior of affected bulbs becomes discolored and rots to varying degrees, with white mycelium forming inside. On the outer surface of the bulb and between the scales, flat sclerotia can be seen, initially white and gradually turning dark brown.
[Pathogen and disease development] This is a fungal disease. The pathogen is a fungus of the genus Sclerotium. It overwinters in the soil as sclerotia, and the pathogen's mycelium spreads through the soil, infecting surrounding plants.
[Control methods]
1. Remove diseased plants promptly when found and burn them; diseased leaves, diseased shoots, and diseased bulbs on them must all be removed as well.
2. Pentachloronitrobenzene can be mixed evenly with fine soil to make a toxic soil and broadcast around the plants.
Control methods for southern blight in hyacinths
[Symptoms] The whole plant wilts, white mycelial strands or rapeseed-like, tea-brown small sclerotia coil around the stem base, and the affected area turns brown and rots. Large numbers of white mycelial strands and tea-brown sclerotia can be seen on the soil surface. The disease occurs at the stem base near the soil surface, causing browning and rot. When the diseased stem tissue is cut open, tea-brown or dark brown rot develops from the outside toward the center; the xylem also discolors upward, and white mycelium growing in a feathery, radiating pattern can spread to the surrounding soil surface; afterward, on the diseased area and the surrounding soil-surface mycelium, sclerotia form that are initially white and later turn yellow-brown and are the size of rapeseeds. After plants become infected, they usually lodge and die as whole plants. On cutting beds, wet rot starts from the callus-formation area of the cuttings and can also cause severe crown and root rot.
[Disease development] The pathogen overwinters in the soil as sclerotia or mycelial strands with diseased plant residues. When conditions are suitable the following year, the sclerotia or mycelial strands produce mycelium for primary infection. The silky mycelium produced by diseased plants extends to contact neighboring plants, or sclerotia are spread by water flow for secondary infection, causing the disease to spread and expand. The disease is severe in continuous cropping, heavy clay soil, low-lying terrain, or in years or seasons with high temperature and high humidity. The pathogen has a wide host range and can harm several dozen kinds of plants, including cacti, orchids, squirrel's tail, cineraria, chrysanthemum, snapdragon, cosmos, dahlia, iris, tulip, hyacinth, lily, and hosta. The pathogen persists as mycelium or sclerotia in diseased residues, diseased plants, wild plants, and soil. Sclerotia can survive in soil for 3-4 years, but their survival period in water and wet soil is very short. High humidity favors the spread of the pathogen, and the peak period of disease occurrence is in summer.
[Control methods] ① Avoid continuous cropping with susceptible plants; base fertilizer applied should be fully decomposed to prevent the fertilizer from carrying the pathogen; provide appropriate ventilation and avoid planting too densely. ② Disinfect the soil before planting, or use 50% thiram, 59 per square meter. Remove diseased plants promptly and burn them, and drench the diseased holes and nearby plants with 5% jinggangmycin aqueous solution at 1000-1600 times dilution, or 50% Tian'an aqueous solution at 500-600 times dilution, 20% tolclofos-methyl emulsifiable concentrate at 1000 times dilution, or 90% dexon wettable powder at 500 times dilution. Drench 0.4-0.5 L per plant (hole). In conjunction with plowing, mix in 100-150 kg of lime powder per 667 sq m to make the soil slightly alkaline, which can inhibit the reproduction of the southern blight pathogen.
Control methods for sclerotium disease in freesia
Sclerotium disease is a common disease of freesia.
SymptomsAfter freesia leaves are affected, they turn pale yellow, plant growth stalls, and later the leaves wilt and fall off easily. The interior of the corm becomes discolored and gradually rots. Long, flat sclerotia can be found between the scales. The sclerotia are initially white and later turn black. The sclerotia are about 12 mm wide.
PathogenSclerotinia bulborum (Wakk.) Rehm. belongs to the Ascomycotina. The pathogen overwinters in the soil as sclerotia, and the mycelial strands it forms can pass through the soil to infect the host. Ascospores produced in spring can also cause damage. This fungus attacks hyacinth, squill, and crocus.
Control methods
1. Carefully inspect bulbs for disease and burn them together with fallen diseased leaves in a centralized manner.
2. Contaminated soil can be sterilized by heating or with chemicals.
3. When planting bulbs, spread 70% pentachloronitrobenzene around the bulbs, then cover with soil. When disease occurs, spray 20% tolclofos-methyl emulsifiable concentrate at 1000 times dilution or 50% vinclozolin at 1000 times dilution. In greenhouses, 10% ling smoke agent can be used.