by Dr. Jerry Sisk, Area Agricultural Agent


Jefferson Parish Office


SEPTEMBER 20, 1997

6640 Riverside Drive, Suite 100
Metairie, LA 70003
504 838 1170
Fax 504 838 1175



1 SOLARIZING YOUR GARDEN.....a chemical free method to combat weeds, insects and diseases

2 PLANTS LEAD THE BATTLE FOR CLEAN AIR... indoor plants work for your good health

3 GALL INSECTS... a problem or a resource???


As we look forward to fall and cooler weather (if there is such a thing), remember that regular weekly watering of plants is needed for maintenance and survival of our landscape plants, our trees and our lawns. Problems which we are likely to run into next spring may simply be results of the recent hot, dry weather and winter stress on our plants.

Garden Bed renovations and preparations should be considered as cooler weather approaches. The addition of ample quantities of organic matter will improve the overall quality of our beds and eventually the quality and the quantity of our plantings.


Sick Building Syndrome

A phrase developed by scientists to describe the acute build up of indoor air pollution, refers to the fact that most Americans spend up to 90 percent of their time indoors, and many of these same people suffer from health problems aggravated or created by "SICK BUILDING SYNDROME".



 Fall Lawn Preparation

Muriate of Potash (0-0-60) may be added to lawns and plants about the 15th of October. Lawns will benefit from the addition of about 2 to 3 lb.. Per 1000 sq. Ft. Water immediately after application. Use no nitrogen- containing fertilizer on lawns till April 15th or later of next year....


 Mistletoe... a serious pest to the survival of many Water Oaks


Mistletoe, will gradually kill back your water oak, and should be considered a serious pest to its survival.... The sticky seeds of this perennial evergreen parasite are spread by birds and animals. The seeds, which are coated with a gelatinous substance, lodge on young branches and germinate.

 A rootlike, penetrating structure grows into the branch and produces a new plant. Excess shading of the leaves of the trees by large mistletoe plants produce die back and severe decline of the affected branches. Control by removing affected branches at least one foot below the infection point.

Scab Disease of Pecan Trees

Scab Disease of Pecan Trees is hard to control due to the need for regular cover sprays which start early in the spring. Clean-up around the tree during this time of year is important to reduce the severity of the disease next year. Pick up and discard leaves, pecan husks, and broken branches.



(The utilization of the Sun and sheet plastic as a sterilant for your garden soil).

 Solarization, a technique used to control insects, weeds, fungi, bacteria, and nematodes in home gardens for some time, has been found to be highly successful for the home owner and also relatively inexpensive.

 "Solarization" or "Tarping" was developed in Israel and has been tested in Universities across the U.S. This combines the use of a clear 1 to 6 mil grade plastic sheeting, which is about three feet longer and three feet wider than the garden plot, with a shovel, a little effort, and the use of a large amount of sunshine.

 Solarization works similar to the greenhouse principle. Following harvesting the garden in the summer or the early fall, till the garden area and rake to remove vines, leaves, and any plant residues from earlier planting. A thorough going over will assure the breaking down of the larger clods. This should be followed by a good deep watering, which will saturate the soil.

 The next step entails digging a shallow trench around the perimeter of the garden. Following this step, cover the garden bed with the clear plastic. The use of 1 mil has been tried and may work, although 3 to 6 mil will probably last longer and be available if needed for another site. Black plastic shouldn't be used because it absorbs the suns rays and won't pass the needed heat on to the soil. You may need to recruit some help to stretch the plastic over the bed area and hold it while you cover the areas around the bed with dirt.

 After filling around the bed on three sides, have your volunteers stretch the plastic so that you can fill it on the fourth side. Clean your garden tools and let the sun do the rest. As the sun's rays pass through the plastic, the heat generated is trapped beneath, similar to a greenhouse. Following days of continuing sunlight, soil temperatures increase dramatically, reaching up to 140 degrees F. at the soil surface, and 102 degrees F. between 12 and 18 inches below the soil surface. The heating effect creates about 100% humidity in the water logged soil.

 Even though the high temperature and humidity over a short period may not have an effect on the pests, the combined effect over the period of about four to six weeks becomes very effective. The destruction of large numbers of insect larvae, weed seeds, bacteria, and fungi follows.

 It may take several days for soil temperatures to reach their maximum beneath the plastic. Therefore cloudy days may delay the temperature rise. Rain or water beneath the plastic will also delay the temperature rise and may create a long delay before the soil temperatures are adequate for the process.

 Research at L.S.U. suggests that with two weeks of consistent sunlight, many of the weed seeds in the top 1/2 to 1 1/2 inches of soil are killed. Although some weed species are resistant to higher temperatures than others, solarization has been shown effective on seeds of goosegrass, annual bluegrass, annual sedges, crabgrass, and dayflower.

 Solarization has been tested and found to be an effective control in reducing verticillium in eggplants, tomatoes, and potatoes; fusarium in tomatoes, cotton, and onions; sclerotium in peanuts, pyrenochaeta in tomatoes and onions, rhizoctonia in potatoes and onions; and nematodes in alfalfa, potatoes and other crops.

 According to the University of California at Davis, solarization may also create soil enhancement. Although many of the fungi, bacteria, and other pathogens are killed, certain fungi that play important roles in the utilization of nutrients by plants, as well as crop development, withstand the high temperatures and survive.

 One theory has it that solarization tilts the balance of soil organisms in favor of the beneficials. At the Idaho Agricultural Research and Extension Center in Aberdeen, Idaho, potato field trials indicated a 97% reduction in verticillium, a 65% reduction in root lesions from nematodes, and measurable yield increases during soil solarization tests.

 The success of solarization is very much dependent on the soil temperatures generated, the soil moisture, and the species of weed seed or organism.

 Following solarization, when removing the plastic and preparing for planting, it is important to disturb the soil as little as possible in order to prevent seeds that are not destroyed by the heat from germinating when they are brought to the soil surface.

 Because this process is entirely dependent on sunlight, in the New Orleans area, the best time to solarize is probably July through late September or October, when

 For optimum results, you probably need two or three weeks of full sunshine days for this process to be most effective.

Adapted from: Solarize Your Garden

by Dick Yost, Organic Gardening.

 Bulb Planting and dividing should be planned to take place in the cooler weather of September and/or October. Day Lilies, Irises and Amaryllis are several of the more popular plants and are represented by many, many varieties.



Scientists are finding, through continuing research, that indoor plants are very effective in the absorption of harmful gases, and also in cleaning the air in many homes and office buildings.

Many tightly sealed homes and offices may prove to be hostile environments for our good healthful living. Can they not hide fumes, both benzene and formaldehyde, from building materials, carpet, and home furnishings; fumes from cleaning products, ozone from copying machinery and printers, and finally second-hand smoke and also radon?

According to a two year study by NASA, many indoor plants can greatly reduce toxic chemical levels in the air inside buildings with poor ventilation. Dr. Bill Wolverton, a NASA research scientist, suggests that fifteen to twenty SPIDER PLANTS OR GOLDEN POTHOS can clean and refresh the air in the average 1,800 square foot home.

Indoor plants are especially effective in filtering from the air three chemicals responsible for many health problems:

  1) BENZENE; a common solvent that is present in inks, oils, gasoline, paints, dyes, detergents, pharmaceuticals, and rubber. Irritates the skin and the eyes, and chronic exposure to low levels may cause headaches, loss of appetite, drowsiness, nervousness, and other health disorders. Benzene has also been linked to cancer and leukemia.

2) FORMALDEHYDE; Found in many indoor environments. Sources may include foam insulation, particle board and pressed-wood products. Consumer paper products, waxed paper, facial tissue, and paper towels may be treated with resins from urea-formaldehyde. Formaldehyde irritates the mucous membranes of the eyes and upper respiratory system. Research suggests links in a rare form of throat cancer to long term occupants of mobile homes.

3) TRICHLOROETHYLENE; is used in metal degreasers, dry cleaning agents, inks paints, lacquers, varnishes and adhesives. This is considered by the National Cancer Institute to be a liver carcinogen.

Research tests have identified plants that work effectively to purify our indoor air. Some that will work well include: PHILODENDRON, SPIDER PLANT, GOLDEN POTHOS, CHINESE EVERGREEN, DRACENA MASSANGEANA, AND PEACE LILY.

Adapted from publications by the Foliage For Clean Air Council, and by the Florida Foliage Association.



Gall INSECTS... a problem or a resource???

Gallnuts from trees have for many centuries been important as agents for dyes they produce soft natural colors of browns, grays, and blacks. They were used in the production of ink until about 1940, and it is their tannin content that makes them valuable in leather processing.

We are probably more familiar to the gallnut as an abnormal growth on the leaves and branches of many shade and pecan trees. Many result from the gall wasp, a tiny insect that stings the plant and stimulates it into excessive growth. The oak apple, a gallnut, or other similar structure becomes the home of the insect. Feeding activities of the larvae that develops inside the gall releases a chemical stimuli that increases the tannin content in those cells of the plant.

Oaks are probably more subject to galls than any other plant. Pecan Trees, however, are plagued by Phylloxera galls which appear as tumor like swellings, or galls, one-tenth to one inch in diameter and appearing on the leaves, leafstalks, succulent shoots, and nuts of new growth. These rounded greenish structures are caused by a soft-bodied insect closely related to the aphid, the pecan phylloxera of which Phylloxera devastatrix Pergande is the most damaging to shoots; severe infections destroying entire limbs.


The insect overwinters in the egg stage in protected areas of the branches, with the young appearing early in the spring about the time the new buds unfold. Insertion of the insects beak into the new growth causes gall formation that soon envelopes the young insect. The insect matures within the gall, lays a large number of eggs, and then dies. As young nymphs hatch from the eggs and develops into the adult winged form, the gall splits open releasing the insects.

This usually occurs in May or June, with several generations occurring each year. The life cycle of the pecan leaf phylloxera, Phylloxera notabilis Pergande, is similar to that of the pecan phylloxera. It creates the 1/8" to 1/4" galls found on the leaves of Pecan Trees. Control of Gall Insects is difficult, but timely early spring cover sprays will give limited control.


Best Regards,

Dr. Jerry Sisk


  A State Partner in the Cooperative Extension System