Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu
Recently, we have had reports of pea fields with reduced seed set. Peas are best adapted to areas with warm days and cool nights. Extended high temperatures in excess of 85º F will cause yield declines in pea by reducing the number of seeds that are carried to harvest.
Experiments have shown that yields can be reduced by as much as 20% with a 5º increase in temperature from 85-90ºF. It has been shown that when peas are exposed to extended periods with high temperatures above 85º F that yields will decline greatly, especially in sensitive varieties. High temperatures in the last 10 days have been >85º F in much of the region.
The critical period where seed set will be reduced is late bloom. If the plant cannot support the full number of seeds due to high respiration and premature stomatal closure, seeds will abort or will not fill.