ISU Extension and Outreach Field Agronomists recently highlighted a significant number of phone calls related to fomesafen carryover injury to corn rotated from 2020 soybeans.
Integrated Crop Management News
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“How much nitrogen (N) has been lost?” is a question we get this time of year, particularly in areas that have received more rainfall. Although most of the state is dry, the southeast part of the state has received above normal rainfall, and there are valid concerns that some N has been lost and additional N could be needed.
While we cannot specifically answer the question of how much N has been lost due to the complexity of the N cycle; below are some approaches we can use in making estimates on the status of N and the potential need for additional N during the growing season.
Canada thistle has been a consistent threat to crop production and perennial habitats since its introduction to the state in the late 1800s. Canada thistle is commonly found in crop fields, pastures, hayfields, CRP, and other full sun habitats. While fall is typically the best time to manage this weed species, late spring, when Canada thistle plants are in the bud or early bloom stage, is a close second for providing consistent herbicidal control. Now is time to be treating Canada thistle in pastures, hayfields, and other non-crop areas if you don’t want to wait for fall.
Multiflora rose (MFR) is a common weed in pastures, CRP, timber and other areas that are not annually disturbed. Now is an appropriate time for treatment of these weeds in pastures and other areas they invade.
Iowa’s most significant soybean insect pest, soybean aphid, has host-alternating biology. Its primary host is buckthorn, an invasive shrub often found in hedgerows and roadside ditches, and its secondary host is soybean. For the majority of the year, soybean aphids exist as cold-hardy eggs on buckthorn branches near leaf buds. As spring temperatures increase, the eggs hatch and a few generations are produced on buckthorn before moving to soybean. In the summer, soybean aphid has multiple, overlapping generations on soybean. During the fall, soybean aphids return to buckthorn.
Black cutworm (BCW) is a migratory pest that arrives in Iowa with spring storms each year. It is sporadic and unpredictable, making it essential to scout to determine whether BCW larvae are present in a field and management is required. Since much of the corn planting around the state is complete and many fields have emerged, now is a good time to begin scouting for larvae.
Performance of preemergence herbicides in many areas of the state may be less effective than normal due to limited rain following application. Although weed emergence following planting was reduced by dry soils and cool temperatures, it is likely that most fields will have some weeds that emerged during this period. Systematic scouting of fields, beginning shortly after crop emergence, will be essential to determine how best to manage weeds throughout the remainder of the season
Pesticide applicators and handlers need to wear, at a minimum, the Personal Protective Equipment (PPE) specified on pesticide product labels. Most pesticide labels require a long-sleeved shirt and long pants. Proper laundering of work clothes that may be contaminated with pesticide residues is essential to reduce pesticide handlers’ short- and long-term exposure to pesticides and prevent the potential of residue cross-contamination onto other clothing.
The growth and development of alfalfa is affected by many factors, including temperature, soil moisture, stand age and even cultivar. Alfalfa growth has been slower than normal due to cool conditions in April. This is a good reminder that using a calendar date to determine when to harvest the first crop of alfalfa may not the best method. In order to accurately predict the optimal time for the first cutting, the University of Wisconsin developed the Predictive Equations for Alfalfa Quality (PEAQ) method.
Bean leaf beetle adults (Photo 1) are susceptible to cold weather and most will die when air temperatures fall below 14°F (-10°C). However, they have adapted to winter by protecting themselves from harsh temperatures under plant debris and loose soil. Each spring, adult beetles emerge from their overwintering habitat and migrate to available hosts, such as alfalfa, tick trefoil, and various clovers. As the season progresses, bean leaf beetles move to preferred hosts, like soybean.