The Agronomy Advisor 5/24/18
What happens to a young corn or soybean plant in dryer than normal conditions?
With moisture conditions heading in to the growing season well below normal, you may be wondering, how do dry conditions affect corn and soybean seedlings and development?
Drought stress occurs when transpiration exceeds the amount of available soil moisture. Recall, transpiration is the process by which plants move water from the soil, through their cell structures, and out into the air. The largest transpiration demand comes at the late vegetative stage through blister for corn, and beginning pod set through the middle of seed fill in soybeans.
When less water is available during the vegetative stage, cell expansion is reduced. This will result in shorter plants with less leaf area. Vegetative development can also occur more rapidly. If high levels of stress occur from V6-V8, the plant could set fewer rows per ear. If the stress occurs from V8-V17, this could result in fewer kernels in each row.
Read more about crop stress at different growth stages by clicking the button below.
Reports from the field
1. We are seeing some ammonium burn on corn, particularly from spring applied anhydrous, but also on Fall applied. Both depth of nitrogen placement and lack of rainfall have contributed to this. Plants affected are smaller in stature, have a purple tinge, and will show browning on the roots.
2. Carryover fomesafen injury is also present in corn fields across the county. Fields where Flexstar was applied last year have resulted in some spotty carryover killing this years corn crop. This could be due to a late application last year of Flexstar, or in areas where limited rainfall didn't flush the residual through the soil profile, or dilute it to a point where it didn't impact this years corn.
3. The first generation of Bean Leaf Beetle is showing up and causing damage on plants from VU to V3. While feeding at this growth stage looks particularly bad, rapid growth in plants should outpace BLB pressure. However, as the season progresses, levels should be monitored as 2nd and 3rd generation will continue to feed on plants.
4. Weed growth is going to increase drastically with these warm temperatures. Some studies show that waterhemp can grow up to 1.5 inches per day in ideal conditions. A general rule of thumb is that marestail will double in size every 4 to 6 days. Keeping that in mind, its important to correctly schedule spraying. We want to schedule late enough to get the longest amount of residual into the growing season, but soon enough to not let weeds reach past that 4-6 inch mark. Its a fine line to walk. Call us if you have any questions on herbicide timing.