Gynoecious Cucumbers: Continual changes in the pickling cucumber industry have greatly increased the need for honeybee pollination. The evolution of mechanical harvesters has resulted in single harvests, and single harvests have necessitated higher plant densities. Plant breeders have released varieties which theoretically produce all female flowers, with male flowers produced on separate plants.
In commercial fields honeybees are usually the only insects pollinating the flowers. At least 8, and sometimes as many as 20 bee visits per flower are necessary to produce a full compliment of seeds inside the cucumber. Honeybees are recommended at the rate of 1 colony for every 40 to 50 thousand plants per acre; 100,000 plants per acre necessitate a minimum of 2 colonies per acre for concentrated yields.
Delayed introduction of rental honeybee colonies has be en shown to increase cucumber per plant yield by over twofold, and the fruit are more uniform in size. These delays were for 5 to 7 days after the first pistillate (female) flowers and staminate (male) flowers appeared. unfortunately, delayed introduction cannot be made in some areas because of the presence of a few bees in the area. Because the delay shows that increased plant vigor improved yield, honeybees never should be brought into cucumber fields until pistillate and staminate flowers are both abundant throughout the field. Some growers scour the field. find a few flowers, and have the bees brought in. By delaying, they would have a more uniform crop.
Cantaloup (Muskmelon), Watermelon, Squash, and Pumpkin: All other vine crops require bee pollination. Usually the rate of 1/2 to l colony per acre is sufficient.
Daytime irrigation of cucurbits can reduce yield by driving off honeybee pollinators and by disrupting pollen germination when water gets into the flower. Also, honeybees will not visit flowers covered or filled with water. Irrigate at night or early in the morning.