Gardening Topics: Lily of the Nile, Identifying Insects

Florida horticulture expert and Director of the Nassau County Extension, Rebecca Jordi, answers gardening and landscape questions.

University of Florida/IFAS Extension Director for Nassau County, Rebecca Jordi, answers questions about landscaping and gardening in northeast Florida.

QUESTION: I had purple and white agapanthus. However, I now have only white flowers. Do the purple flowers change to white? TD

JORDI: Interesting question. Although we know hydrangea flowers can change color by the soil pH we know agapanthus flower (A.K.A. Lily of the Nile) color is not subject to variation regarding soil pH. There are specific instances where variegated cultivars of shrubs, such as Chinese privet, Ligustrum sinense ‘Varigata’, may revert to the solid color invasive parent. But I have not heard of purple agapanthus flowers altering its color. However, I do know the purple cultivars are not as cold hardy as the white variety. I believe you told me yours were growing in pots which made them slightly more susceptible to any cold temperatures. It may well be the purple varieties did not survive our unseasonably cold snap this late spring whereas the white ones have reproduced and thrived. ?

QUESTION: Can you identify these insects for me? They are all over my kale and leafy vegetables. MW

Harlequin Bug (Photo UFIFAS)
Harlequin Bug (Photo UFIFAS)
JORDI: These are some of the easiest insects to identify because of their beautiful coloration.

Harlequin Bug, Murgantia histrionica, is an important insect pest of cabbage and similar crops in the southern half of the United States. Harlequin bugs can destroy the entire crop if not managed properly. This insect is classified as a piercing/sucking insect because it sucks the plant’s vascular tissue fluid. The removal of the fluid from the plant causes it to wilt, turn brown and ultimately die.

Plants commonly attacked by the harlequin bug include crucifers such as horseradish, cabbage, cauliflower, collards, mustard, Brussels sprouts, turnip, kohlrabi, and radish. In the absence of these favorite hosts, tomato, potato, eggplant, okra, bean, asparagus, beet, weeds, fruit trees, and field crops may be eaten. Hand-picking and destroying the insect pests and egg masses may make a difference especially if small numbers of insects are detected. The easiest and most effective control of harlequin bugs is to hand remove them in the fall and spring before they have a chance to lay eggs. Chemical control can be accomplished by using insecticidal soap (not dish soap) on the young nymphs. Apply insecticidal soaps in early morning, before the bugs are active, to maximize effectiveness. Do not use neonicotinoid insecticides or broad spectrum insecticides as they can harm our important bee populations. http://edis.ifas.ufl.edu/in152

QUESTION: What is wrong with my ficus tree leaves? I have been using Neem oil and nothing is working. SD

Weeping Ficus Thrips (Photo UFIFAS)
Weeping Ficus Thrips (Photo UFIFAS)
JORDI: The real cause of the issue is Weeping ficus thrips, Gynaikothrips uzeli. The thrips feed on expanding leaves causing purplish red spots on the lower leaf surface. The leaves become curled and galled, and prematurely drop. Treatments must be applied to protect leaves while they are expanding. Once damage has occurred and populations are developing in tightly curled leaves, adequate coverage with insecticides is extremely difficult.

There are no specific recommendations for this thrips, however, pesticide recommendations for other types of thrips feeding on ornamental plants may work. Some research suggests drenching with dinotefuran (Safari) or acephate (Orthene) provided good control but I realize you are reluctant since you have a toddler and want to reduce any pesticide exposure to the child.

Tip pruning of infested plants will remove the food source of the thrips in addition to any thrips and eggs present on these new shoots. These thrips are commonly preyed upon by a predatory bug, which many times causes the populations of thrips to drop. However, your plant is enclosed in a patio and will have little chance of getting a predatory insect.

You may continue to treat it but you might consider removing the plant and throwing it away. If you decide to destroy the plant, consider placing it in a large lawn bag and tossing it in the garbage. I would not allow other landscape plants to be exposed to this pest. This information comes directly from the UF/IFAS Tropical Research and Education Center.

Rebecca Jordi
Rebecca L. Jordi
Nassau County Extension Director
UF/IFAS Environmental Horticulture
543350 U.S. Highway #1
Callahan, FL 32011
904-530-6351
http://nassau.ifas.ufl.edu

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