What to Do About Acute Bacterial Wilt in Cotton? Causes and Control Methods

Fusarium wilt symptoms in mature plants take several forms. Leaves may also show yellowing-type and net-vein-type patterns, and defoliation occurs easily. On severely affected plants, the top leaves are crinkled and deformed, dark green in color, with shortened internodes and a stunted plant form. After rain, an acute wilt type often appears, with the cotton plant suddenly losing water. The leaves wilt and turn green-wilted rapidly, droop, and often drop off leaving bare stems.

Disease pattern

Cotton Fusarium wilt mainly overwinters in the seeds of diseased plants, diseased plant residues, soil and manure. The transport of infected seeds and infected oilseed cake fertilizer is the main cause of disease outbreaks in new areas. Farming operations such as cultivation, management and irrigation in cotton fields of affected areas are important factors in short-distance spread. The roots, stems, leaves and boll husks of diseased plants can produce fungal spores under high humidity, which spread with airflow and wind-blown rain to infect surrounding healthy plants.

The occurrence of Fusarium wilt is closely related to temperature and humidity. Generally, symptoms begin to appear when soil temperature is around 20°C, and a peak of disease occurrence forms when soil temperature rises to 25-28°C; when soil temperature rises above 33°C the pathogen is suppressed and symptoms temporarily disappear, then after autumn when soil temperature drops to around 25°C a second disease peak appears. After summer rainstorms or in rainy years, the disease is severe because soil temperature drops. The disease is heavy in cotton fields that are low-lying, have heavy clay soil, are somewhat alkaline, have poor drainage, receive excessive nitrogen fertilizer, are treated with inadequately decomposed infected manure, are under continuous cotton cropping, are roughly cultivated, or have many root-knot nematodes.