May 15, 2008

Timely Tips for May – Part 2

By Andy Wilson, Horticulturist, Pinellas County Extension

Got Oleanders? Got Caterpillars?- Oleanders in our area are routinely attacked by oleander caterpillars, orange caterpillars with tufts of long black hairs scattered over the body. They are voracious feeders and they can strip most of the leaves from the plants in a surprisingly short periooleander catepillard of time. The damage is unattractive but not life-threatening to the plants. Applications of sprays containing Bt (Bacillus thuringiensis) generally give good control. There are several generations of these caterpillars per year so it is helpful to check the plants regularly for them.

Flower Thrips on Gardenias- Gardenias add a heavenly scent to many gardens at this time of year but the life span of individual blossoms can be shortened by flower thrips. These small insects feed on the sap of the flower petals, causing the petals to turn brown prematurely. The thrips can also invade flower buds before they open, sometimes causing the buds to drop off without opening. Spraying the plant with a systemic insecticide like imidicloprid or acephate will usually control them.
Thrips on Crotons- Types of thrips that feed on plant leaves are often a problem on crotons in the spring months. On crotons the damage usually shows up as a loss of color in the lower leaves, with leaves eventually turning a tan color. Infested leaves will have small brownish spots of excrement on their undersides. Damaged leaves drop off the plant beginning at the base of the stem moving upward. Leaf feeding thrips can be controlled with several products including light horticultural oils. More information on thrips can be found here:

psocid webbingTree Mummies?- If the trunk or branches of one of your trees develops a gauze-like or silk stocking-like covering there is no need to panic. The tree will not be harmed. The webbing is spun by psocids, small insects that feed on lichens that live on the trunks of trees. Psocids produce the webbing to protect themselves from the elements while they feed. Although the webbing can look quite eerie, psocids do no harm whatsoever to the tree they’re on and no control is needed. Eventually the webbing will weather away.

Summer Color - For color in the summer landscape consider these heat tolerant bedding plants: vinca, globe amaranth, amaranthus, moss rose, purslane, celosia, melampodium, Dahlberg daisy, ornamental pepper, salvia and wishbone flower. It’s helpful in work 2 to 3 inches of organic matter (peat, compost, etc.) into the soil before planting. This improves the water and nutrient holding capacity of the soil. More information on selection, planting and care of bedding plants can be found here:

Mango Harvest- Early maturing varieties of mangos like ‘Zill’, ‘Edward’, ‘Saigon’, ‘Florigon’ and ‘Earlygold’ are ready for harvest as early as May. To determine whether the fruit is mature enough for harvesting look for fruits in which the shoulders and nose of the fruit have “filled out” or broadened. Often there is a touch of color in the skin of the fruit at this time (on varieties that color at maturity). Mature fruits will usually ripen to eating quality in 3 to 8 days indoors at room temperature. Once they are fully ripened the fruits can be refrigerated for later use.

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