This year continues the chain of growing seasons with extremes and rapid changes beyond our long-term experiences. This made for periods of both stress and favorable crop growth despite the planting dates. Frost, potentially killing in the northern half of Iowa, is expected between October 11-13. USDA data indicate a wide range of maturity due to planting date, but the periods of hot weather scattered through September and early October may have reduced the potential for very high moisture corn and soybean. Variability will be the key issue to manage in 2019 corn and soybeans.
Integrated Crop Management News
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Very variable weather this season will result in variable corn and soybean yield within and between fields. Entire fields or portions of fields were planted later than usual or were not planted. This will result in variable removal of phosphorus (P) and potassium (K) with harvest. Reduced yields combined with continued low market values create uncertainty about P and K fertilization decisions for the 2020 season.
The plentiful rain in September has provided ideal conditions for establishment of winter annual weeds, thus many no-till fields will have dense stands of these weeds going into winter (Fig. 1). The wetter springs we have encountered recently complicate getting spring burndown applications made in a timely matter.
Taking time to verify combine adjustments made in the shop match with the field conditions may seem time consuming but can minimize harvest loss as well as profit loss. This article discusses how to evaluate for pre-harvest loss and losses during harvest, and the types of in-field adjustments that can be made to minimize harvest losses.
To determine what types of adjustments may be warranted, assess if losses are due to pre-harvest loss or due to the harvesting process i.e. from the combine head or the threshing cylinder and the separation sieves.
Fall is one of the best times for managing perennial and biennial weeds found in pastures or other areas maintained in perennial grass. As perennials prepare for the upcoming winter they move energy reserves from shoots to their perennial vegetative reproductive structures (e.g. rhizomes, perennial rootstocks). Systemic herbicides applied at this time are translocated along with the energy reserves to the reproductive structures, therefore providing more consistent control than applications made at most other times of the year.
Corn earworm (Photo 1) is common in Iowa corn. It is a migratory pest, migrating from the southern and southeastern U.S. every summer. There are two general fights to the Midwest every summer, but the first flight is not of economic concern. Iowa’s corn is more vulnerable to infestation of the second flight, arriving in late July. Yield losses can occur in late-planted cornfields, where caterpillars can infest >50% of plants. It is more common to see corn earworm issues in sweet corn, white corn, popcorn, and seed fields.
The escalating spread of herbicide-resistant weed populations has become a production challenge in the corn-soybean based cropping system of the Midwest. With the evolution of weed resistance to major herbicide groups used in corn and soybean, we have a limited number of herbicide options left, which is even more disconcerting as no new herbicide site of action has been discovered in the past three decades. A new site of action coming to the marketplace in the next 5-8 years would also be a rare event.
Harvest is quickly approaching and most are anticipating a highly variable corn and soybean crop. Below are some reminders for regular maintenance, adjustments, and final checks to make sure your combine is ready to hit the fields soon.
With delayed planting across the state in 2019, it is important to monitor crop development to determine unique grain drying needs this fall.
With delayed planting across the state, it is important to plan ahead for potential harvest challenges. Scout your fields for crop development to determine whether you might have potential problems with immature, frost-damaged grain, and wet grain.
Frost-damaged soybean will have a slower dry-down in the field and may produce green/yellow soybean with above-normal shrink from drying. The green color may subside within two weeks of maturity if allowed to dry in the field or after several weeks of aeration.