The following are high priority exotic pest threats for the Australian cotton industry as identified through the development of the cotton industry biosecurity plan (IBP). All of these pests would have serious consequences should they enter and become established in Australia.
Information about other pests of cotton is available from the cotton industry page on the Plant Health Australia website.
To improve biosecurity measures on your farm, include exotic pests when undertaking routine pest surveillance activities. Ensure that all surveillance activities, for both endemic and exotic pests, are recorded. Consultants carrying out the surveillance should be provided with pest fact sheets that show key symptoms for identifying characteristics of the target exotic pests.
Fusarium wilt (exotic races)
Fungus – Fusarium oxysporum f. sp. vasinfectum
Found in every cotton-growing region in the world
Risk is from new strains establishing to which the local cotton varieties have little or no resistance
External symptoms: stunted growth, wilted leaves, yellowing, browning, eventual death
Internal symptoms: brown discolouration of stem tissue
Spread by spores in soil, water and infected plant material
Look for Fusarium symptoms on varieties that should be resistant
Photo by Merle Shepard, Gerald R Carner, and PAC Ooi, Insects and their Natural Enemies Associated with Vegetables and Soybean in Southeast Asia, United States, Bugwood.org
Spider mites (exotic species)
Mites – e.g. Tetranychus turkestani, T. pacificus
Spider mites high risk to the Australian cotton industry are present in North and South America, Asia and Africa
Small (less than 0.5 mm), red or green in colour and have eight legs
Exotic species may not respond to current pesticides or may attack crops not normally affected by spider mites
Look for intense crop damage, unusual looking mites or the presence of mites on the upper leaf surface (T. pacificus only)
Long distance spread may occur with infested plant material
Verticillium dahliae: Photo by Howard F Schwartz, Colorado State University, United States; Bugwood.org
Verticillium wilt (defoliating strains)
Fungus – Verticillium dahliae
Found in China, Iran, Israel, Mexico, Peru, Spain, USA, former USSR
Risk is from new, defoliating strains establishing to which the local cotton varieties have little or no resistance (non-defoliating strains present in Australia)
Extremely wide host range, including vegetable, fruit and broadacre crops
Leaf mottling, vascular peppering, total defoliation, boll shedding
When the stem is cut lengthways, vascular discolouration exhibits flecking of the inner tissues
Spread by spores in water, soil and infected plant material, clothing and equipment
