Drought: Implications for near-term management decisions in field crops
The recent trend in higher than normal temperatures paired with lower than normal precipitation puts Michigan field crops at risk.
Below are some considerations raised by Michigan State University Extension educators and specialists that growers may want to consider implementing if drought conditions continue or intensify.
Prevent fires during wheat harvest
Manage potato leafhoppers in alfalfa and dry beans
Watch for spider mites in soybeans
Scout irrigated fields for western bean cutworms
Fungicides: To spray or not to spray?
Most foliar diseases are favored by rainy or humid weather conditions. We have seen very little foliar diseases in corn or soybeans with the warm and dry conditions that we have been experiencing. The greatest chance of returning a profit on a fungicide application occurs when conditions favoring disease are present and when disease develops. The decision to spray should be based on the presence of disease risk factors, such as the susceptibility of a hybrid or variety, previous crop, field history and weather.
In general, a susceptible corn hybrid or soybean variety is more likely to have a greater response to a foliar fungicide than a resistant hybrid or variety. Cropping history will have influence on disease as many foliar pathogens survive on residue, i.e., corn after corn or soybeans after soybeans promote disease. The disease history of a field should also be taken into account; fields with a disease history should be monitored carefully so that the best decision can be made. And, finally, the weather; the hot and dry conditions that we have been experiencing so far have not been favorable for most foliar diseases. If you do decide to spray, consider leaving replicated, non-treated test strips in the field to determine if you are getting a benefit.
Harvest alfalfa early or not at all
Get to the root of soybean problems
Drought symptoms usually occur in localized areas within fields and the severity of the symptoms also varies between the affected areas. There are two conditions that explain the spotty occurrence and severity of drought symptoms:
- Variations in the capacity of the soils to hold water.
- Variations in the plant’s ability to utilize the available water.
When is supplemental nitrogen recommended for soybeans?
Numerous university research trials have shown that nitrogen fertilizer applications to soybeans are not profitable. This is because soybeans are able to obtain up to 75 percent of their nitrogen from bacterial colonies (nodules) living on their roots. However, if the nodules are not present in sufficient numbers, a supplemental nitrogen fertilizer application will produce an economic return.
Forego foliar feeding until moisture returns
Drought stress much earlier in the growing season than what is typically expected for Michigan may have resulted in stunted plants with compromised root systems and, therefore, growers are considering foliar fertilizer applications. Regardless of application method, nutrient uptake, availability and transport are severely limited without sufficient water. Under high temperature stress and dry soil conditions, plants attempt to conserve water by closing stomata, which are microscopic pores or holes in the leaf and stem surfaces of plants used for gas exchange. Water soluble fertilizers applied as foliar sprays are intended to be applied to the leaf surface with nutrient uptake occurring through these open leaf stomata. Under the hot, dry weather conditions that much of Michigan is encountering, foliar nutrient applications will be mostly ineffective as plants close their stomata to conserve what little moisture may still be available.
Controlling tough weeds in tough conditions
In dry conditions, weeds tend to “harden off,” making herbicide absorption by weeds more difficult. This can make weed control much more challenging, especially with herbicides like glyphosate. To control some of these tougher to control weeds in Roundup Ready crops, increasing the rate of glyphosate to 1.13 or 1.5 lb a.e./A and including ammonium sulfate (AMS) at a rate of 17 pounds of AMS per 100 gallons can improve weed control successes. If using other herbicides that tend to cause herbicide injury (e.g., Cobra, Cadet, Raptor, etc.), consider spraying in parts of the day when temperatures are cooler to decrease chances of extreme herbicide injury.
Stay hydrated and know the signs of heat stroke
- MSU Extension’s Drought Resources