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July 9, 2020

2020 U.S. Soybeans Starting to Bloom, Dryness is a Concern

Author: Michael Cordonnier/Soybean & Corn Advisor, Inc.

The condition of the 2020 U.S. soybean crop held steady last week to 71% rated good to excellent. The soybeans are 31% blooming compared to 8% last year and 24% average. The soybeans are 2% setting pods comparted to 1% last year and 4% average.

I think it is a little too early to trim the soybean yield because the soybeans are just starting to bloom, but if the forecast verifies and the dryer than normal conditions are prolonged, the soybean yields will probably also decline in the coming weeks.

Moisture Stress and Soybean Pod Development - A ridge of high pressure over the Midwest has resulted in hotter and dryer conditions. At this stage of the growing season, soybeans are not as sensitive to hot and dry conditions as corn. Corn has only one chance at ear development and pollination, whereas soybeans have multiple chances at setting pods and pod development. If the hot and dry conditions persist for a prolonged period of time, it could result in stunted soybeans with lower yield potential.

Under drought conditions, a soybean plant will abort many of its flowers, in fact, the majority of flowers are naturally aborted even under normal conditions. When there is a drought, it is common to see soybean plants where no pods have been set at a number of nodes on the stem. The node is where the leaf attaches to the stem and that is where the flowers develop and eventually turn into pods.

Soybean plants continue to flower during the summer, so if the moisture stress is eliminated, the plant can retain the new flowers and set new pods. Soybeans always have the chance to recuperate some of the potential losses if the weather improves later in the season.

If there is significant drought during the critical pod development period from about late July through about mid-August, the soybean plant then has less time to recuperate, so there will be lower yields as a result.

If drought occurs later in the season, then some of the seeds inside the pod may not develop and the seeds may end up being smaller and lighter than normal and thus a lower yields.