You may notice premature flower bud drop on hibiscus and gardenia. This can be caused by insects, as well as cultural or environmental problems. Insects called thrips and midges can damage the unopened bud. Thrips and midges are very small, but you can often see them if you open a bud that has dropped from the plant. Beneficial insects like ladybugs and others can help control these pests.
, Temperature and water fluctuations can also cause buds to drop and random leaves to yellow. In addition, too much or not enough fertilizer can also stress a plant, resulting in bud drop. Nematodes can take over a root system, creating a water deficiency and nutritional stress on the plant that also results in bud drop. Scout your garden regularly for insect pests. Also watch for beneficial insects like ladybugs, green lacewings and minute pirate bugs. These will help control common pests like aphids, whiteflies and mites.
, Many pests can be controlled by removing the insect or an infested branch. If you find that you need to treat with a pesticide, always try the least toxic method first. Pesticides like neem oil, fish oil and insecticidal soaps will control many insects and not contaminate your harvest. Use chemical pesticides with caution; read and follow the label carefully; and pay close attention to the number of days you must wait after spraying before you can harvest. Also, be certain that the product label lists the crop you are going treat.
Information from Carol Suggs and Theresa Badurek of the Pinellas County Extension Service and from the Hillsborough County Extension Gardening Almanac. Go to the extension websites at pinellascountyextension.org and hillsborough.extension.ufl.edu.