Tomato Pollination and Bumblebee Visits
While visiting a tomato field this week I saw the tell-tale signs on the flowers that this field was being visited by bumble bees that were pollinating the tomato flowers. In the field wind movement is usually enough to cause pollination in a tomato flower, but at times there are very calm days and nights with very ‘heavy’ air and little wind movement. However, even with wind action it is always beneficial to have bumble bees perform buzz pollination, which can greatly in-crease fruit set. Bumble bees perform buzz pollination by firmly biting the flower cone, then rapidly vibrating their wing muscles which dislodge the pollen from within the flower. The bumble bee leaves visible bite bruises on the flower cone, which can be used to verify that pollination has occurred (fig. 1). Good pollination of the tomato flower is important be-cause the final size and weight of fruit is largely determined by the number of seeds set, which is ultimately due to the quality of pollination and fertilization. In figure 2, flower 1 has been visited by a bumble bee approximately 4-6 times, while flower 2 has been visited just 2-3 times and flower 3 has not been visited. In the field the more visits the better. Not surprisingly this particular field of tomatoes I was in had a very heavy fruit set (fig. 3). Growers should try and look for this flower bruising from time to time to see if they are having sufficient bumble bee visits (>3-4 is good) in their tomato field which will increase fruit numbers, fruit size and fruit quality. Little or no visits may indicate a poor pollinator environment which could mean poor pollination and therefore poor fruit quality.
This article appears in July 2023, Volume 14, Issue 5 of the Vegetable and Fruit News.