While scouting alfalfa this week we observed a field that had pea aphids at population densities that greatly exceeded the economic threshold of 400 pea aphids per 30 sweeps in alfalfa that is taller than 10”. The populations were so extreme that in 30 sweeps we were collecting approximately 1,000-3,000 pea aphids.
While scouting pea fields last week, we noticed some populations of tarnished plant bugs. Although these insects are rarely an issue in most crops, they can cause considerable damage to field peas due to pod feeding.
Following the first cutting, alfalfa fields should be monitored for the presence of blister beetles. These beetles are usually considered beneficial insects. However, blister beetles can become an issue when large populations of them are present in alfalfa fields.
During the SDSU Extension Field Pea & Lentil Tours in the Harrold and Fort Thompson areas last week, small populations of pea aphids were observed in each of the fields. The aphid populations were well below the recommended thresholds and shouldn’t be much of a concern at this time.
SDSU Extension will be hosting a tour of the Small Grain Crop Performance Trials located near Selby, SD. The tour is set for July 6, 2017 at 5:00pm (CST). Attendees will have the opportunity to view field peas, winter and spring wheat, and oats varieties to see how they perform in the field.
We are finding large numbers of alfalfa plant bugs showing up in alfalfa fields throughout South Dakota. By directly feeding on alfalfa plants, alfalfa plant bugs can become an issue for seed production as well as forage quality.
Similar to last year, many parts of South Dakota are experiencing dry conditions. Many areas have gotten some moisture, but this has not been enough to make a difference in crop production.
Sorghum and milo planting are well under way in South Dakota, and we are starting to receive reports of stand issues with some earlier planted fields. Upon inspection, these fields were found to have patches where it appeared the seed had been fed on, or the cotyledons had been removed.
SDSU will be hosting plot tours of the Field Pea and Lentil Variety Trials on June 22nd and 23rd in Central South Dakota.
A windshield survey seems to indicate an increase in field pea acres around Central South Dakota. Powdery mildew is a common disease in field peas occurring, at times, in late planted or late maturing fields.