What are the symptoms of bacterial wilt in peppers?
Pepper bacterial wilt is a soil-borne bacterial disease, and the main route of invasion by the pathogen is through wounds on the crop's roots. So, what are the symptoms of pepper bacterial wilt?
1. What are the symptoms of pepper bacterial wilt?
The main symptom is that the plant rapidly turns brown, wilts, and dies, while the stems and leaves remain green. When the browned part of the diseased stem is squeezed by hand, a milky white bacterial fluid is discharged.
2. Conditions for the occurrence of pepper bacterial wilt
This disease occurs frequently in continuous cropping fields and in alluvial soil fields with a high groundwater table and high humidity. Seedbeds should be disinfected and the bed soil replaced in a timely manner, and crop rotation should be carried out in a planned way; at the same time, grafting cultivation should be adopted as a preventive measure. Once diseased plants are found, they should be removed immediately and burned.
3. Pattern of occurrence of pepper bacterial wilt
The pathogen mainly overwinters in the soil with diseased plant residues. In the following spring, the overwintered pathogen spreads via rainwater and irrigation water, invades through wounds, and after a relatively long period of latent infection and multiplication, when the plants reach the mature stage and encounter conditions of high temperature and high humidity, it spreads upward, multiplies in the vessels of the vascular bundles, and blocks the vessels or causes cell poisoning, resulting in leaf wilting. The pathogen can also pass through the vessels into adjacent parenchyma cells, causing water-soaked irregular lesions on the stems. When the soil temperature reaches 20°C, disease centers appear, and at 25°C the disease peaks. After long rain or heavy rain followed by clearing, the temperature rises sharply and the disease worsens.
4. Control methods for pepper bacterial wilt
(1) Agricultural control
1. Carry out crop rotation. Planned crop rotation can effectively reduce the bacterial load in the soil and lessen the occurrence of the disease.
2. Improve the soil.
3. Optimize cultivation methods. Adopt high-ridge or semi-high-ridge cultivation with matching field ditch systems to reduce field humidity, and at the same time increase the application of phosphorus, calcium, and potassium fertilizers to promote robust crop growth and improve disease resistance, which can lessen the occurrence of bacterial wilt.
4. Grow strong seedlings. Use nutrient pots, fertilizer blocks, and hotbeds for raising seedlings to produce short, sturdy seedlings, so as to enhance the crop's disease resistance and tolerance.
5. Spray micronutrient fertilizers. Spraying micronutrient fertilizers can promote the growth and development of the plant's vascular bundles and improve the plant's disease resistance and tolerance.
(2) Chemical control
Root drenching can be done with 100-200 mg/kg agricultural streptomycin or new streptomycin or 4% pyrimidine nucleoside antibiotic or Gaoke mefenoxam + hymexazol. Apply 0.25-0.5 kg of the solution per plant, once every 10-15 days, for 2-3 consecutive times. While root drenching, it is also necessary to spray solutions such as: 50% copper green emulsifiable concentrate 500-fold dilution, 14% copper ammonia complex aqueous solution 300-fold dilution, Gaoke 30% mefenoxam + hymexazol, 4% pyrimidine nucleoside antibiotic, 77% copper hydroxide wettable powder 500-fold dilution, 50% DTM wettable powder 500-fold dilution, or 72% agricultural streptomycin wettable powder 4000-fold dilution. Spray once every 7-10 days, for 2-3 consecutive sprays, and the effect on controlling pepper bacterial wilt is significant.
The pepper bacterial wilt pathogen enters the vascular bundles after invading the crop and blocks the transport system through multiplication, so that water cannot enter the stems and leaves, causing bacterial wilt. Once the pathogen enters the vascular bundles, it is very difficult to eliminate, so in production, prevention is the key to controlling bacterial wilt.