Check gardenia for whitefly before they settle in for summer


Though individually tiny, whitefly can have a big impact on gardenia shrubs if populations build up to high levels.

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Published: Thursday, May 16, 2013 at 04:08 PM.

Almost every yard in the south has at least one gardenia. Planted by generations of gardeners for their exotically fragrant white blossoms, these tough evergreen shrubs are salt tolerant, drought tolerant and deer resistant. One thing they cannot resist is the tiny whitefly. These petite pests cause gardenia leaves to turn yellow and plants to appear dark or sooty. If this describes the gardenia in your yard now is the time to check for whitefly and determine if treatment is needed.

Identifying whitefly

Adult whiteflies look like tiny white moths and are around one tenth of an inch in length. Like many pests, they are most often found on the backside of leaves. When infested plants are disturbed, whiteflies will flutter around for a few minutes and then resettle on the plant. Giving a bush a quick shake is an easy way to scout for whitefly at this time of year.

In reality, whiteflies are neither flies nor moths, but are most closely related to mealybugs, aphids and scale insects. They feed on plant sap with needle like mouthparts. Plants that are heavily infested with whitefly often have lots of yellow leaves and clouds of whitefly emerge when the plant is disturbed. In addition, like their scale, aphid, and mealybug relatives, whitefly secrete honeydew, a sticky sweet substance that attracts ants and wasps. Black sooty mold, a harmless fungus that grows on the honeydew, can cover whitefly infested plants, causing the leaves and stems to appear dark and sooty.

There are several types of whitefly in the south. Some feed on vegetables. Others are more common in greenhouses and on houseplants. The type of whitefly found on gardenia is known as the citrus whitefly. While citrus whitefly has been reported to feed on 38 different types of plants, they are almost always found only on gardenia or citrus trees in our area.

If your gardenia has lots of yellow leaves, or if the leaves and stems look dark and sooty you should check for whitefly. Recently emerged adult whitefly will be easily visible on the new growth. If you look on the back of older leaves you will likely find both adult and immature whitefly. In their immature stage whitefly resemble their scale relatives, looking like light orange, round, flat discs stuck to the back of the leaf.

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