A, anthrax,
1. The acute symptoms
Yam anthracnose major hazard leaf and stem.Leaf disease spot from the blade tip or just begin to produce green stain shape small spots, then expanded to brown to dark brown round to oval or shaped big spot, disease spot in the middle is gray brown to gray, with lines, and has a small black point.Infected newborn stem spindle irregular spots, around the middle gray, black, severe upper and lower disease spot confluent, cause the whole black and dry, minister of disease with a little black points.Position, the disease can infect leaf, petiole, vines, and kind of potato, the impact on the output is big, is one of the main problems of hemp yam.Specific performance is as follows:
(1) infection blades.Disease spot more and bigger, gradually, a joint cause leaf withered and yellow, litter, commonly known as "yellow";(2) infection petiole.With the expanding of disease spot, petiole around a week or two thirds when causes leaves green also is a litter, commonly known as "green";(3) infection vines.Symptoms and petioles onset, same disease spot spot the upper die of the disease when vines around a week.(4) infect potatoes.Yam emergence begins when the upper frame, early aboveground plant wilting, and pull with the hand, whole plant can gently pull up, find the rhizome and kinds of potato joint began to rot, typical for anthrax symptoms.
2. The pathogen and pathogenesis regularity
Sexual generation for wai small clump shell, fungi belonging to ascomycotina.Asexual spore anthrax for glue, belong to the imperfect bacteria and fungi.With mycelium and conidium plate in the disease department or with the sick body left overwintering in the soil.In June the following year to produce a large number of conidium spread by wind and rain, primary infection and many times to infect, widening spread, continue to harvest.Temperature of 25 to 30 ℃, relative humidity 80% susceptible.The weather is warm and wet or big dew heavy fog the, favorable partial nitrogen or plant to yu all, bad ventilation pervious to light can make the disease worse.Germs main wintering in disease tissues, spread by wind and rain, high temperature and heavy rain.
3. The method of prevention and cure
Agriculture: (1) the incidence of plot more than 2 years of rotation;(2) remove the sick body after harvest, burned, and soil of the commune;(3) using high stand management, reasonable density, improve the field microclimate.(4) strengthen field management, timely row weeding, row dirt stains;Reasonable fertilization, give priority to with rotten organic fertilizer, cultivating strong seedling, enhance plant disease resistance.
Control: (1) choose hartz trichoderma leaf type 300 times liquid foliar spray, combined with soils irrigated chong hartz trichoderma leaf type prevention;(2) after onset, 12% rosin acid copper 800 times foliar spray, spray once every 7 days, 2 to 3 times.
Second, the disease
1. The acute symptoms
Hemp yam disease major hazard of leaf, stem tendril.Leaf disease, many from the tip, or just began to form small spots dark green oily be soiled, gradually expand the irregular shape disease spot, was killed after severe tissue brown dry gradually;Petiole disease, the disease spot leaf and stem from petioles spreading, disease of brown gradually;Vines, and leaf symptoms similar to the early period of 4 to 5 cm above the ground layer black necrotic, serious when all the plants died.The rainy season vines base water is the main cause of disease pathogenesis.
2. The method of prevention and cure
Agriculture: (1) choose disease-resistant varieties;(2) implement the crop rotation, the commune content, increasing organic fertilizer application and micronutrient fertilizer, improve soil structure, improve the performance of protecting fertilizer water promote root development, plant robust;(3) watch, found a small amount of Ye Guo, immediately remove buried deep.
Agent: control period to seize the prevention after the rain, the 12% rosin acid copper 800 times foliar spraying, spraying must seedling and all spray to the ground, when thoroughly kill sterilization source.
