Integrated Crop Management News

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High Reproduction of SCN Populations on PI 88788 Resistance is Frightening

October 28, 2022
Soybean Cyst nematode females on roots.

Iowa State conducts soybean cyst nematode (SCN) experiments in fields rented from farmers in all of Iowa’s crop reporting districts. Spring soil samples from each study area are used to test the SCN population in the field for levels of reproduction on soybean breeding lines with SCN resistance genes. The results of testing in 2022 revealed some SCN populations with 75% to 90% reproduction on PI 88788, the source of SCN resistance genes present in almost all of the soybean varieties available in Iowa. This high level of reproduction makes complete loss of effectiveness of PI 88788 SCN resistance seem possible within several years. The number of varieties with more effective Peking SCN resistance is increasing every year, but the rate of increase is not keeping pace with the increase of reproduction of SCN populations in Iowa fields on PI 88788 resistance. An active, integrated approach to managing SCN in Iowa is more important than ever.

Options for Fall Grain Drying and Marketing

October 20, 2022
Grain storage bins.

With harvest in full swing and while conditions have generally been good for in-field drying this fall there are still some corn fields in areas of the state with moisture levels in the low to mid 20s.

Time of the Year to Sample Fields for SCN

October 10, 2022
Soil sample map.

Getting fields sampled for SCN is a task that should be on every farmer’s to-do list this fall. SCN soil samples can be collected from corn fields after harvest to determine what levels of the nematode are present to infect the 2023 soybean crop. Results of soil samples collected from fields of harvested soybeans this fall will show if SCN was present and reveal what effect the nematode might have had on soybean yields in 2022. Reproduction of SCN is greatest in dry years, and SCN egg numbers in the soil are expected to be high in soybean fields this fall. This article outlines guidelines for sampling fields for SCN, gives information on where to send SCN soil samples, and provides guidance on managing fields that are infested with SCN.

Beware of Dry Conditions When Soil Sampling and Interpreting Test Results

October 5, 2022
Soil testing in dry soils

October began dry across most of Iowa except for some areas in southern and southeast Iowa. These conditions are allowing for rapid harvest progress. The outlook for the rest of the month calls for lower than normal rainfall. Below normal rainfall since August until the soil sampling time may result in lower than expected soil test results for phosphorus (P), potassium (K), and pH. Therefore, farmers and crop consultants should interpret those soil test results with caution.

Keep an Eye Out For This Weed

October 5, 2022
Dense population of Asian copperleaf.

While Iowa weed communities change constantly, it is rare that a species new to the region is discovered. Asian copperleaf (Acalypha australis) was first discovered in Iowa in 2016 in a corn field near Cedar Falls. Prior to this discovery, the only documented infestation in North America was within New York City. The plant was recently found in a soybean field in Grundy County, nearly 30 miles from the original infestation (Figure 1).

Fall Burndown Treatments for Winter Annual Weeds

September 30, 2022
Henbit seedlings under a corn canopy.

Recent rainfalls are likely to result in the establishment of winter annual weeds. Many fields may have dense stands of these weeds going into winter (Figure 1). It is often difficult to achieve timely burndown of these species in the spring, so farmers with persistent problems should consider making a fall burndown application to control winter annuals.

Prioritize Pasture and Non-crop Weed Control!

September 30, 2022
Weeds growing in a pasture.

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).

Keep Monitors, Sensors and Scales Accurate During Harvest

September 29, 2022
Corn moisture's influence on yield monitor error.

When heading to the field for harvest, it’s important to make sure your monitors, sensors and scales are getting accurate numbers. Taking the time to calibrate your combine yield monitor is the first step in making sure you are using high quality yield data to make decisions in your operation.

Sap Beetles in Corn: Are they Pests?

September 23, 2022
Sap beetle.

Sap beetles are a relatively common insect in cornfields, typically seen each year around harvest. People usually notice sap beetles (and other ear-feeding pests) while doing pre-harvest yield checks. Adult sap beetles are usually less than ¼ inch long and oval. Most are dark colored and sometimes have orange or yellow spots (Photo 1). Sap beetles can be distinguished from other beetles in corn by their antennae, which have a knob at the end. Larvae may also be found on corn ears. The larvae are small and white with a light brown head, and they turn yellowish as they mature.