What Pesticides Work Well to Control Cotton Fusarium Wilt and Verticillium Wilt

The damage caused by cotton Fusarium wilt and Verticillium wilt to cotton cultivation is devastating; they spread relatively quickly and are very difficult to eradicate. What pesticide works better for cotton Fusarium wilt and Verticillium wilt?

1. What pesticide to use for cotton Fusarium wilt and Verticillium wilt

1. The peak outbreak period of Fusarium wilt occurs around cotton squaring, in mid-to-late June; Fusarium wilt strikes fiercely and causes severe damage. If heavy rainfall occurs, it can favor a large-scale epidemic of Fusarium wilt. In early-to-mid June, spray with 25% bromothalonil WP at 1500-2000 times dilution for control, and spray 1-2 more times at an interval of 7-10 days, which can effectively control the peak outbreak and epidemic of cotton Fusarium wilt.

2. The peak outbreak period of Verticillium wilt is during the cotton flowering and boll stage in July and August. At this time, if cotton plants become diseased, it causes sparse boll setting, more shedding, reduced yield, and deterioration in quality. In addition, because the cotton plants are relatively large, control is more difficult. In mid-to-late July, control should be carried out promptly by spraying with 25% bromothalonil WP at 1000-1500 times dilution, and spraying once more at an interval of 7-10 days, which can effectively control the occurrence of Verticillium wilt.

3. Use 30% oxadixyl-azoxystrobin at 800 times dilution, 12.5% zhiweiling at 200-250 times dilution, and 30% metalaxyl-hymexazol at 600 times dilution, applying 1 drench each at the initial and peak stages of disease, with 50-100 ml of the prepared solution per plant, achieving 80%-90% control efficacy.

2. Occurrence Pattern of Cotton Fusarium Wilt and Verticillium wilt

Cotton Fusarium wilt and Verticillium wilt mainly spread and expand through bacteria-carrying cottonseed, cottonseed hulls, cottonseed cake, soil, diseased plant residues, fertilizer, flowing water, and farm management tools.

When the cotton Fusarium wilt and Verticillium wilt pathogens in the soil encounter suitable temperature and humidity, the pathogen spores or microsclerotia germinate into hyphae, invade through the root hairs or wounds of the cotton root system, pass through the epidermal cells, grow within the subcutaneous tissue, enter the vessels of the xylem, reproduce within the vessels, and produce large numbers of small spores, which are transported with plant nutrients to all parts of the plant.

Because the hyphae and spores reproduce in large quantities and stimulate adjacent parenchyma cells to produce gelatinous substances and other materials that block the vessels, the pathogen can also produce toxins, causing the plant to wilt and die.

For Fusarium wilt, when soil temperature is low and humidity is high, the hyphae grow quickly, and the first disease peak appears in the field in mid-to-late June.

When summer temperatures are relatively high, development slows. In autumn, when there is more rain and the temperature drops, the second disease peak appears.

The optimum temperature for the onset of Verticillium wilt is 25-28°C. Above this temperature, disease development slows, and when it reaches 35°C, symptoms become latent. In the north, the peak disease period is during the cotton flowering and boll stage in July-August.

The hosts and host plants of the cotton Fusarium wilt pathogen number more than 40 species, half of which are wild plants; the hosts of cotton Verticillium wilt number 660 species. Neither pathogen harms crops such as wheat, corn, rice, sorghum, foxtail millet, and broomcorn millet.

For the control of cotton Fusarium wilt and Verticillium wilt, disease-resistant varieties should be selected at planting time, seeds should undergo pesticide treatment, and field management should be done well, with rational crop rotation and stubble rotation.