The effects of extreme heat experienced in many locations of the nation will continue to be felt by tomato growers for weeks to come.
Tomatoes, and particularly the flowers, are sensitive to too hot or to too cold temperatures, according to a grower newsletter article written by Jerry Brust, integrated pest management vegetable specialist with the University of Maryland.
Continual exposure to daytime temperatures above 95 degrees Fahrenheit and nighttime temperatures above 80 degrees at can compromise pollen viability.
Most pollen is shed between 10 a.m. and 4 p.m.
Three or more hours of 103 degrees on two consecutive days can cause fruit set failure.
And night-time temperatures play a more important role than day-time temperatures.
That's because ideal fruit set occurs between 60-70 degrees.
Nighttime temperatures above 75 degrees interfere with pollen tube and can prevent normal fertilization, causing blossom drop.
Prolonged high humidity also can affect fruit set by hindering pollen shed or causing pollen grains to bind together.
Poor pollenation also can cause undersized fruit.
High temperatures during fruit ripening can cause internal whitening.
Unfortunately, Brust writes, not much can be done to combat heat other to ensure the plants receive enough water and not to over-fertilize them.