Treatment Recommendations
How should I structure my management program to control Asian soybean rust?
Dow AgroSciences offers Laredo® fungicide, a sterol inhibitor product from the triazole chemical class, which offers both a preventive and curative defense. Laredo is available through 2006 for control of Asian soybean rust in soybeans through Section 18 exemptions.1 Curative activity is available on infection levels of less than 5 percent in the lower canopy. Strobilurin fungicides, on the other hand, are preventive and should be applied before infection has occurred for acceptable results.
A triazole product should be your first application, because the visual signs of soybean rust are not evident for up to five to 10 days post infection. Triazoles are highly systemic. This activity offers protection to new growth from spray deposits on stems below developing new foliage. After a triazole premix is applied, a second application may be made with a strobilurin or strobilurin + triazole tank-mix or pre-mix.
Laredo delivers up to 21 days of residual activity when used in a preventive or curative application. The length between sprays will be determined by the extent of any existing infection and the level to which conditions favor disease development. Fungicides from the strobilurin and nitrile chemistry groups only work by protecting the leaf surfaces that the fungicide reaches. Leaf surfaces not covered by a strobilurin or nitrile does not offer residual protection against soybean rust.
Good coverage is essential to cure or prevent soybean rust successfully. For coverage, use nozzles that provide upper-fine to medium-sized droplets (175 to 430 microns volume median diameter) and are aimed at the crop. Use sufficient spray volume and pressure to ensure the product is driven through the canopy and coverage is achieved on upper, mid- and lower canopy leaves. Never cut rates. Always use manufacturer recommended rates.
Soybean rust fungicides can be tank-mixed with commonly used crop protection products, such as Lorsban®-4E insecticide or many weed control products like FirstRate® herbicide. Tank-mixes with herbicides calling for low spray volumes, low pressure and large droplet size would not be favorable for optimal lower crop canopy penetration. Use jar tests to ensure compatibility. To optimize disease control, focus on proper sprayer setup and timing, but don’t compromise proper spray timing to accommodate tank mixes.
Contact us to learn more about the protection Laredo® fungicide offers against soybean rust.
