cross section of plant stem

Endemic diseases such as Verticillium and Black root rot can inhibit production and be costly for growers and consultants. Integrated disease management (IDM) strategies are important for controlling and reducing the impact diseases can have on farm. In back-to-back cotton fields, the disease risks are higher, increasing the importance of using a range of IDM strategies such as planting resistant varieties.

The development of resistant varieties has been a prominent method for managing major cotton diseases including Fusarium wilt. The industry has developed a ranking system (F rank for Fusarium wilt and V rank for Verticillium wilt) to allow growers and consultants to compare the disease resistance levels of different commercially available varieties. The ranking indicates the resistance performance of varieties as a percentage of industry nominated benchmark varieties. The number of trial comparisons used to determine the number reported in brackets. The best commercial varieties available currently have an F rank of 152 and V rank of 112. F and V ranks are published annually by one of the three CottonInfo partners, Cotton Seed Distributors.

Resistant varieties will slow the build-up of disease inoculum in the soil, in contrast to susceptible varieties. Slowing the build-up of inoculum levels is essential for the sustainability of cotton production in disease-affected fields. When weather conditions are particularly conducive to disease development, disease incidence may increase even with the use of resistant varieties. Therefore, it is important to be using a multiple IDM strategies including balanced crop nutrition, preparing optimal seedbeds and sowing when temperatures are 16°C+. From a variety perspective, it is also important to consider seedling vigour particularly when watering up or planting early to get your crop off with best possible start.

More information on integrated disease management strategies are available in the Cotton Pest Management Guide, while the latest disease rankings are available in the CSD Variety Guide and online at www.csd.net.au

This blog is part of a year long program from CottonInfo, with the themes aligned with the 2020 CottonInfo cotton calendar and the UN's International Year of Plant Health. For more information, view the calendar, or contact the CottonInfo Technical Lead for Biosecurity, Sharna Holman