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2022 Midwest Vegetable Guide

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Pollination Midwest Veg Guide 2022 31 Pollination Reviewed by Ben Phillips – Sept 2021 Pollination is the transfer of pollen from the male portions of the flower (stamens) to the female portions of the flower (pistils). This process is vital to the production of many vegetable crops, including cucumber, cantaloupe, pumpkin, squash, and watermelon. Some crops (such as tomato) are self-fertile, but wind or bees must vibrate the flowers to release pollen for fertilization. Honey bees are often thought of as the most prevalent pollinator for vegetable crops, but studies show that many species of native bees — including bumble bees and squash bees — play a vital role in pollinating many vegetable crops. Tomato, for example, benefit from the "buzz pollination" that bumble bees can provide. Honey bees are unable to buzz pollinate, and therefore do not play a role in tomato pollination. The squash bee, a North American native, is an important pollinator of pumpkins and other squash crops. Native bees are often active earlier in the day and at cooler temperatures than honey bees. To ensure pollination, many vegetable growers rent honey bee hives rather than manage their own hives. Since honey bee colonies are occasionally in short supply, growers should communicate frequently with their bee providers. In addition to renting honey bee hives, growers can improve the pollination services of native and non-native bees by increasing on-farm habitats. The Xerces Society for Invertebrate Conservation ( ) and Pollinator Partnership ( offer guides, plant lists, and other resources about building on-farm bee habitats. At least 90 crops grown in the United States depend to some extent upon bees as pollinators, either for seed or fruit production. The exact number of honey bee hives needed to pollinate a crop depends on a number of factors, including the strength and condition of colonies, magnitude of the natural pollinator community, amount of wild flower material competing with the crop, attractiveness of the crop to bees, projected yield, and weather. The following are guidelines for the number of hives to use when supplemental pollination is desired: cantaloupe (2 to 3 colonies per acre) cucumber (2 to 3 colonies per acre) pumpkin (1 colony per acre) squash (1 colony per acre) watermelon (1 to 5 colonies per acre — the pollination requirements of seedless varieties are generally greater than seeded) The following vegetables will set fruit without bees, but bee activity has been shown to increase yields: eggplant okra lima bean pepper Honey bees do not assist in the pollination of the following crops, but will collect pollen and/or nectar from them: pea sweet corn snap bean tomato Do not place hives in a field until the crop's flowers are available to visit. If the hives are placed before the flowers are available, the bees will forage to surrounding areas and may not forage sufficiently in the crop that needs pollination. Bees forage best within about 100 yards of the colony. Therefore, if the field is large, the bees should be distributed in clusters around the field. Bees also require a source of clean water. If not available nearby, set out a shallow container with fresh water. Approximate Time from Pollination to Market Maturity Under Warm Growing Conditions Vegetable Days to Market Maturity Bean 7-18 Cantaloupe 40-50 Corn, fresh market 1 18-23 Corn, processing 1 21-27 Cucumber, pickling (3/4 to 1-1/8 inch diameter) 4-5 Cucumber, slicing 15-18 Eggplant (2/3 maximum size) 25-40 Okra 4-6 Pepper, green stage (max size) 45-55 Pepper, red stage 60-70 Pumpkin, jack-o-lantern 60-90 Pumpkin, baking 65-75 Squash, summer, zucchini 2 3-4 Squash, winter, butternut 60-70 Squash, winter, hubbard 80-90 Squash, winter, acorn 55-60 Tomato, mature green stage 34-45 Tomato, red ripe stage 45-60 Watermelon 40-50 1 From 50% silking. 2 For a weight of 0.25-0.5 lbs. Bees and Pesticides When foraging for pollen and nectar in flowering plants, honey bees, as well as bumble bees and native bees (solitary bees), may be exposed to a variety of different pesticides (insecticides and miticides) that can cause direct or indirect toxic effects. Direct toxicity occurs when honey bees are immediately killed after exposure to wet sprays or dried pesticide residues on leaves or flowers. Indirect toxicity is

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