The plant diseases we have in our crops are caused by many different organisms, including fungi, bacteria, viruses, nematodes and others. Fungicides are pesticides used for controlling fungal and fungal-like diseases. This week, I wanted to bring a new M.S.U. Extension MontGuide to your attention that is about fungicide use in field crops and specifically talk about how to reduce the risk of fungicide resistance developing.When using fungicides for disease management, the principles of integrated pest management should be used to avoid resistance development. This includes such things as preventative cultural practices, monitoring, acceptable pest levels, mechanical controls, biological controls, and responsible use.
Preventative cultural practices include using high quality, pathogen-free seed, crop rotation, using an adapted crop variety, optimal seeding rate, planting date, irrigation practices where able, fertilization and sanitation, such as breaking the “green” bridge.Monitoring involves scouting crops for pests regularly and getting them accurately identified. You can then determine at what level the pest can or will be tolerated.
Mechanical control methods include removing infected plants from the crop to prevent reproduction and spread of the disease. Natural biological controls can also mitigate pest damage. For plant diseases, these can include beneficial insects predate on or parasitize insect vectors of plant viruses.When a pesticide is needed, be responsible and follow all label restrictions and use the best application methods possible to target the disease of interest. If a lack of efficacy is suspected, leaved an untreated strip to compare with treated areas. If the level of disease is the same, then a symptomatic sample should be sent to the diagnostics lab. Other recommendations to prevent fungicide resistance include selecting and using fungicides correctly, rotating the use of fungicide modes of action, limiting the number of applications of fungicides in a particular mode of action each season, mixing modes of action in blends or tank mixes, using fungicides at the recommended rates and following all label directions. Following these directions should dramatically reduce your risk of developing resistance.