1. Pea root rot
[Symptoms] The disease can occur from seedlings to mature plants, and is more common during the flowering period. It mainly harms the roots or stem bases. The leaves of the diseased plants turn yellow first, and then gradually develop to the middle and upper parts, causing the whole plant to turn yellow and wither. The main and lateral roots turn dark brown or earthy red, and the nodules and root hairs are significantly reduced. In mild cases, the plant will become dwarfed, the stems will be thin, and the leaves and branches will wilt or wither. The pathogen spreads through the soil, diseased and damaged tissues and seeds, and invades through the seed coat and lateral roots, which is easily confused with wilt. Generally, the disease is severe in drought years.
[Prevention and control methods]
Select disease-resistant varieties; mix seeds with pesticides: mix seeds with 20% triadimefon emulsifiable concentrate at 0.25% of the seed weight, or mix seeds with 75%WP chlorothalonil at 0.2% of the seed weight, both of which have certain effects.
2. Pea brown spot
[Symptoms]
It mainly harms leaves, stems and pods. The infected leaves show irregular lavender spots. Under high temperature and high humidity conditions, the spots spread rapidly and cover the entire leaf. The diseased leaves then turn yellow, twist and die. Some show dark brown irregular ring spots with black spots in the center. Cause of the disease The pathogen mainly overwinters on the seeds and spreads with wind and rain. Early sowing or cold damage, heavy soil, high humidity, excessive nitrogen fertilizer application, and vigorous plant growth are all prone to disease.
[Prevention and control methods]
(1) Agricultural prevention and control: Severely diseased fields should be rotated with non-leguminous vegetables for 2-3 years. At the same time, seeds should be disinfected. After pre-soaking in cold water for 4-5 hours, soak in 50℃ warm water for 5 minutes, and then cool and dry before sowing. Appropriately close planting and increase potassium fertilizer.
(2) Chemical control: At the early stage of the disease, spray 50% benomyl wettable powder suspension 800 times, 70% WP thiophanate-methyl 500 times, 75% WP Chlorothalonil 600 times, once every 7 days, spray 2-3 times in a row.
3. Pea powdery mildew
[Symptoms] At the early stage of the disease, the leaves are light yellow spots, which expand into irregular powdery spots. In severe cases, the front and back of the leaves are covered with a layer of white powder, and finally turn yellow and die. In the later stage of the disease, the powdery spots turn gray and grow many small black particles.
[Prevention and control methods] At the early stage of the disease, spray 25% triadimefon wettable powder 2000-3000 times, or 70% thiophanate-methyl wettable powder 1000 times, or 50% WP carbendazim 500 times, or Baume 0.2-0.3 degree lime sulfur mixture for spray control. Spray once every 10 to 20 days, and spray 2 to 3 times in a row.
4. Pea brown streak
[Symptoms] Mainly damages leaves, stems and pods. The leaves are infected with irregular light purple spots. Under high temperature and high humidity conditions, the spots spread rapidly and cover the entire leaf. The diseased leaves then turn yellow, twist and die. Some are dark brown with irregular ring spots, and black spots appear in the central necrosis. Cause of the disease The pathogen mainly overwinters on the seeds and spreads with wind and rain. Sowing too early or suffering from low temperature and cold damage, or soil is too sticky, humidity is too high, or nitrogen fertilizer is applied excessively, and the plants grow vigorously, which are prone to disease.
[Prevention and control methods]
(1) Agricultural prevention and control: It is best to rotate with non-leguminous crops for more than 3 years, and disinfect the seeds. Soak the seeds in warm water for 4-5 hours, then transfer them to 55℃ warm water for 5 minutes, cool them in cold water, dry them and sow them. Appropriately plant densely and increase potassium fertilizer.
(2) Chemical control: spray 500 times of 50% mixed sulfur suspension or 600 times of 75% thiophanate-methyl wettable powder at the early stage of the disease, once every 7 days, and spray continuously for 2-3 times.
5. Bean stalk black miner
[Damage symptoms] Bean stalk black miner is a pest of the genus Blackminer of the family Muscidae in the order Diptera. It is a widely distributed borer, mainly harming leguminous crops. From the newly hatched larvae, it bores into the main stem through the young and tender parts of the leaf veins and petioles, and eats the pith and wood. If prevention and control are not timely, it will cause serious yield reduction.
[Prevention and control methods]
Agricultural control: appropriately adjust the sowing period to stagger the peak egg-laying period of adults to reduce damage;
Chemical control: the applied pesticide is 40% dimethoate, 40% oxydemeton-methyl, 50% fenitrothion, or 45% phoxim emulsifiable concentrate, all of which need to be diluted 1000 times with water, and 75 kg of liquid is applied per mu.
6. Pea leaf miner
[Damage symptoms] Pea leaf miner belongs to the order Diptera, family Phyllostomidae, also known as rape leaf miner, commonly known as leaf archer, leaf clipper, leaf maggot, etc. It is a polyphagous pest with more than 130 host plants. It mainly harms peas, broad beans, chrysanthemum, celery, cabbage, radish and kale.
[Agricultural control]
(1) Agricultural control: After harvesting vegetables, remove fallen leaves and weeds in the field in time, burn or compost them to reduce the insect population in the field.
(2) Chemical control: Choose pesticides with short residual effect and easy photolysis and hydrolysis. In addition, since the larvae are leaf miners, the use of pesticides must be carried out at the critical moment from the peak of egg laying to the early hatching period. Spray 800 times of Methionine (21% enhanced cyanamide EC), 2500 times of 2.5% deltamethrin or 20% cypermethrin, 2000 times of 10% bromomethrin EC, 1500 times of 10% cypermethrin EC, 3000-4000 times of 1.8% insect mite light and 1.8% harmless kill at the appropriate time. Good control effect can be achieved by spraying at the appropriate time.
7. Comprehensive control of pea diseases
(1) Select disease-resistant varieties: Generally, fine-pod peas are more disease-resistant than large-pod peas; implement crop rotation: Because the root secretions of peas affect the nodule activity and root growth of the plants in the next year, they should not be planted continuously. Crop rotation can be implemented with non-leguminous crops such as melons and fruits or gramineous grain crops.
(2) Seed disinfection: 0.3% of the seed weight can be mixed with 70% thiophanate-methyl, or 50% carbendazim wettable powder plus 75% chlorothalonil wettable powder (1:1) and sowed after 48 to 72 hours of sealing.
(3) Strengthen field management: Rationally apply fertilizers, plant densely, avoid planting in low wetlands, and use high ridges or ridge cultivation. Increase the application of phosphorus and potassium fertilizers, avoid partial application of nitrogen fertilizers, and spray rutin regularly to improve disease resistance; maintain good field hygiene: timely remove diseased plants and plants damaged by insects, as well as straw and root stubble after harvest, and bury or burn them in a centralized manner to reduce the source of disease and insects.
