Citrus Update

May 2
May 2, 2008
Coteau-Bayou Blue gets jump start at business world
May 6, 2008
May 2
May 2, 2008
Coteau-Bayou Blue gets jump start at business world
May 6, 2008

The warm and fairly dry spring conditions have caused an increase in populations of a certain citrus pest in many home and commercial orchards. The citrus red mite (Panonychus citri) has a small red body with several white hairs (setae) arising from the back and sides of the abdomen. Each female can lay two to three eggs a day and may lay 20 to 50 eggs. The mite eggs are red with white setae in the top center. They can develop from egg to egg in 12 days. Populations increase in spring, late summer and early fall in response to new growth, because they prefer young leaves, but will also infest fruit.

Citrus red mites feed on the cells of leaves and fruit. Damage to foliage produces a pale stippling that is visible on the upper leaf surface. Stippling of the green fruit disappears when the fruit change color. When large populations feed on fruit, the silvering may persist. They have multiple generations and are fed on by a large predator population of mites, lady beetles, lace wings, and the six-spotted thrip.

According to the “Louisiana Home Citrus Production Guide,” an application of light horticultural oil should keep these populations down. In addition, the miticide Kelthane can be tank-mixed as per label directions to increase the success rate.

Blackberry Season

Harvest blackberries as early as possible in the morning when the day is relatively cool. Fruit harvested when temperatures are high spoil more quickly than fruit harvested at lower temperatures. Berries should be picked firm-ripe, handled carefully and stored in a cool place as quickly as possible. Most berries need to be harvested every other day for best results. Handle them carefully to prevent bruising and crushing. The quality of blackberries deteriorates rapidly when they are held at 75 degrees or above for more than 24 hours. Berries may be stored for four to five days at 32 degrees to 35 degrees with a relative humidity of 90 percent.

Citrus Fruit Drop

Typical citrus trees go through three distinct periods of fruit drop. First is the drop of about 70 to 80 percent of the flowers during and immediately following bloom. The second drop occurs a couple of weeks later, involving small fruit of pea-size to marble-size. The third drop occurs now through May, involving larger fruit, almost golf ball in size. Navels will drop again in mid-summer and in late summer. A few fruit on all citrus will continue to drop through final harvest, but that is normal and cannot be prevented.

Citrus Weed Management

Weeds are considered plants growing out of place and can compete with crops for moisture, light, and nutrients. In addition, weeds can be a negative regarding hindering cold protection when dealing with a citrus crop in South Louisiana.

Weeds are considered economic pests if they reduce the growth, health and survival of young trees, or the time to come into bearing and ultimately fruit production. Eventually, trees are deprived of whatever portion of resources that vegetation utilizes. The more competitive the vegetation, the more adversely it alters tree physiology, growth, fruit yield and quality.

Weeds also have various effects on tree performance, referred to as interference, including reduced efficacy of low volume irrigation systems, interception of soil-applied pesticides, and lowered grove temperatures during cold weather events.

Mechanical removal or chemical applications can reduce weed populations and increase the productive vigor of citrus trees in home and commercial orchards. Most homeowners can simply use a non-selective product containing glysophate that will remove any weed if applied as per label directions. You must be very careful as this type of product will injure or kill plants it contacts through foliar contact. It can even be taken up by herbaceous stems or exposed cambium areas (such as an injury to the bark due to weed eater damage or another type or mechanical injury).

You should target the area directly under the canopy of the trees to reduce weed pressure as well and competition for nutrients and moisture. Commercial producers have additional options for trees three years of age and older to provide almost season long weed control. Homeowners will have to re-apply glysophate two to three times per year to maintain adequate bare ground under your citrus trees. This will pay off in the winter when the temperature drops below 26 degrees as the heat will be able to radiate out of the ground through the canopy of the tree to provide you up to six degrees of cold protection through your weed management methods.

Question of the Week:

My lawn has a dark gray to black growth on the leaf blades. What is this and what should I do to control it?


The recent rains have caused Slime Mold to return to lawns and other turf areas. Slime mold is gray to purple spores attached to the leaf surface areas on turf grasses, rocks and other substances. What you are seeing is the fruiting structures of the fungi. It usually is underground but comes up during moist periods. Slime Mild does not pose any threat to plant or human, as it is not toxic. Spray it off with a stream of water from your garden hose.

For more information on these and other horticultural topics, call the Lafourche Extension office at 985-446-1316 or come by 402 West 5th Street in Thibodaux. You can also visit our web site at