How to Control Pea Pests and Diseases? Latest Technical Methods Tutorial
Peas are the world's fourth-largest legume crop, and China is the world's second-largest pea producer after Canada, holding a pivotal position in global pea production. The main diseases of peas include root rot, brown spot, powdery mildew, and brown streak, while the main pests include the bean stem black leafminer and the pea leafminer. Let us take a look at pea pest and disease control techniques below!
Pea Root Rot
[Symptoms] The disease can occur from the seedling stage to the mature plant stage, with infection most common during the flowering period. It mainly damages the roots or the base of the stem. The leaves of diseased plants turn yellow first, then gradually spread to the middle and upper parts, causing the entire plant to turn yellow and wither. The main and lateral roots partially turn dark brown or earthy red, and root nodules and root hairs are noticeably reduced. In mild cases, plants become stunted with thin stems, and leaves and branches appear wilted or withered.
[Causes] The pathogen spreads through soil, diseased plant residues, and seeds, invading through the seed coat and lateral roots, and is easily confused with Fusarium wilt. Generally, the disease is more severe in dry years.
[Cultural Control] Select disease-resistant varieties such as Gansu's Gongjingxuan, hemp pea, Xiaodou 60, Xiaodou 704, and others.
[Seed Treatment] Treating seeds with 20% triadimefon emulsifiable concentrate at 0.25% of seed weight, or with 75% chlorothalonil wettable powder at 0.2% of seed weight, both have certain effects.
Pea Brown Spot
[Symptoms] It mainly damages leaves, stems, and pods. Infected leaves show irregular light purple spots. Under high temperature and high humidity conditions, the lesions spread rapidly, covering the entire leaf. The diseased leaves then turn yellow, twist, and die, and some show dark brown irregular concentric ring spots with small black dots produced in the necrotic center. [Causes] The pathogen mainly overwinters on seeds and spreads through wind and rain. Early sowing or exposure to low-temperature chilling injury, or heavy clay soil, excessive humidity, or excessive nitrogen fertilizer leading to excessive plant growth, all make the disease more likely to occur.
[Cultural Control] In severely affected fields, practice a 2-3 year rotation with non-legume vegetables. Also disinfect seeds by pre-soaking in cold water for 4-5 hours, then soaking in warm water at 50°C for 5 minutes, then cooling, drying, and sowing. Plant at appropriate density and increase potassium fertilizer application.
[Chemical Control] At the early stage of the disease, spray 50% benomyl wettable powder suspension at 800 times dilution, 70% thiophanate-methyl wettable powder at 500 times dilution, or 75% chlorothalonil wettable powder at 600 times dilution, once every 7 days, for 2-3 consecutive sprays.
Pea Powdery Mildew
[Symptoms] At the early stage, light yellow small spots appear on the leaf surface, which expand into irregular powdery patches. In severe cases, both sides of the leaves are covered with a layer of white powder, and finally the leaves turn yellow and die. In the later stage, the powdery patches turn gray and produce many small black granules.
[Control Methods] At the early stage of the disease, spray 25% triadimefon wettable powder at 2000-3000 times dilution, or 70% thiophanate-methyl wettable powder at 1000 times dilution, or 50% carbendazim wettable powder at 500 times dilution, or lime sulfur mixture at 0.2-0.3 degrees Baume. Spray once every 10-20 days, for 2-3 consecutive sprays.
Pea Brown Streak
[Symptoms] It mainly damages leaves, stems, and pods. Infected leaves show irregular light purple spots. Under high temperature and high humidity conditions, the lesions spread rapidly, covering the entire leaf. The diseased leaves then turn yellow, twist, and die, and some show dark brown irregular concentric ring spots with small black dots produced in the necrotic center. [Causes] The pathogen mainly overwinters on seeds and spreads through wind and rain. Early sowing or exposure to low-temperature chilling injury, or heavy clay soil, excessive humidity, or excessive nitrogen fertilizer leading to excessive plant growth, all make the disease more likely to occur.
[Cultural Control] It is best to practice a rotation of more than 3 years with non-legume crops, and disinfect seeds by soaking in warm water for 4-5 hours, then transferring to warm water at 55°C for 5 minutes, then cooling in cold water, drying, and sowing. Plant at appropriate density and increase potassium fertilizer application.
[Chemical Control] At the early stage of the disease, spray 50% mixed sulfur suspension at 500 times dilution, or 75% chlorothalonil wettable powder at 600 times dilution, once every 7 days, for 2-3 consecutive sprays.
Bean Stem Black Leafminer
[Damage Symptoms] The bean stem black leafminer is a pest of the genus Melanagromyza in the family Agromyzidae of the order Diptera. It is a widely distributed boring pest that mainly damages legume crops. Newly hatched larvae bore through the leaf veins and tender parts of the petioles into the main stem, feeding on the pith and xylem. If not controlled in time, it will cause severe yield loss.
[Cultural Control] Adjust the sowing date appropriately to avoid the peak egg-laying period of adults, thereby reducing damage.
[Chemical Control] Apply 40% dimethoate, or 40% omethoate, or 50% fenitrothion, or 45% phoxim emulsifiable concentrate, all diluted 1000 times with water, applying 75 kg of spray solution per mu.
Pea Leafminer
[Damage Symptoms] The pea leafminer belongs to the order Diptera, family Agromyzidae, also known as the rape leafminer, commonly called the arching leaf worm, leaf maggot, etc. It is a polyphagous pest with more than 130 host plants. On vegetables, it mainly damages peas, broad beans, garland chrysanthemum, celery, Chinese cabbage, radish, and cabbage.
[Cultural Control] After vegetable harvest, promptly remove residual plant debris, fallen leaves, and weeds from the field, and burn or compost them to reduce the field pest population base.
[Chemical Control] Choose pesticides with short residual activity that are easily photodegraded and hydrolyzed. In addition, because the larvae damage leaves by mining, pesticide application must seize the critical period from the peak egg-laying stage to the early hatching stage. Spray 800 times dilution of Mieshabi (21% synergized fenvalerate-malathion emulsifiable concentrate), 2500 times dilution of 2.5% deltamethrin or 20% fenvalerate, 2000 times dilution of 10% bromo-malathion emulsifiable concentrate, 1500 times dilution of 10% fenvalerate-malathion emulsifiable concentrate, or 3000-4000 times dilution of 1.8% and 1.8% Haitongsha. Spraying at the appropriate control time can achieve good control results.
Integrated Control of Pea Diseases
1. Select disease-resistant varieties: Generally, thin-podded peas are more disease-resistant than large-podded peas.
2. Practice crop rotation: Because pea root exudates affect the root nodule activity and root growth of plants the following year, peas themselves should not be continuously cropped. They can be rotated with non-legume crops such as melons and fruits or gramineous grain crops.
3. Seed disinfection: Treat seeds with 70% thiophanate-methyl at 0.3% of seed weight, or mix 50% carbendazim wettable powder with 75% chlorothalonil wettable powder (1:1) for seed treatment, and seal for 48-72 hours before sowing.
4. Strengthen field management: Fertilize and plant at reasonable density, avoid planting in low-lying wet areas, and use high beds or ridged cultivation. Increase phosphorus and potassium fertilizer application, avoid excessive nitrogen fertilizer, and regularly spray brassinolide to improve disease resistance.
5. Maintain field sanitation: Promptly remove diseased plants and pest-damaged plants as well as straw and root stubble after harvest, and bury them deeply or burn them in a centralized manner to reduce sources of disease and pests.
6. Chemical methods: For the control of the bean stem black leafminer, the pea seedling stage should be the focus of control. Use 1.8% abamectin emulsifiable concentrate at 2000 times dilution, or 50% phoxim emulsifiable concentrate at 1000 times dilution, or 48% chlorpyrifos emulsifiable concentrate at 1000 times dilution for root drenching or spraying.