By: Zvi Howard Wener / Chief Agronomist / Zviw@zeraim.co.il

Flowers: Most melon varieties have male, female and perfect (male and female parts in the same flower) flowers. The staminate (male) flowers are on the main stem and they appear first. The lateral stems produce the pistillate (female) flowers and often the first node of the lateral branch has a perfect flower. To get fruit set there must be some aid to pollination because the pollen is large and sticky. Even in a perfect flower the heavy, sticky pollen tends to fall to the outside of the flower and not towards the pistil (female part). Therefore, bees are used to facilitate pollination and get fruit set.

Bees: In melons the hives should be placed in the field or greenhouse only when open flowers begin to appear on the main stem (male flowers). The bees are attracted to the pollen and nectar of the flowers but the quantities are relatively low compared to many other crops and neighboring crops can often attract the bees away especially in springtime. Moreover, if the hives are placed too early (before the open flowers) then the bees might migrate to other fields because other crops will be more attractive.

Melon flowers open in the morning and become shriveled by the end of the day. On the day the flowers open they need about 6-8 visits by the bees for good pollination. Pollination begins in the morning when the flower opens and the pollen levels are high and is usually completed by noon or early afternoon. The pollen levels decrease very quickly during the day. In hot dry areas the pollen is probably only effective in the early morning. In order not to interfere with the bee activity it is recommended to do the agrotechnical work on the plants in the afternoon.

The normal recommendation is one bee per plant or 2-2.5 hives/ha with more bees required if there is a high density planting. In greenhouses the hives should be on the outside of the structure with the entrance facing an opening in the greenhouse. The hive should be very close to the opening so that the bees can easily enter both the greenhouse and the hive. In the field the hive should be placed in the field as opposed to the border of the field.

Pesticides: Care should be taken when applying pesticides to avoid killing the pollinators. Insecticides with short residual activity are best and should be applied in the late afternoon/early evening since the pollinating insects are usually active in the morning. This is true of all cucurbits.