by Kathryn Courtney
Last year was a very hard gardening year. Harvey had many of us with yards full of water and water in our houses as well. We were all finally getting back on our feet and then came the great freeze of 2018. Many plants that survived previous freezes did not survive this one. previous freezes did not survive this one. All of this added up to a great stress on plants that did survive. Stressed plants are very vulnerable to soil diseases, fungal problems and problems with insect pests. The camellias and azaleas in our gardens mostly made it through the flood and freeze, but these events left them very stressed and fragile. A perfect environment for attacks from tea scale and lace bug insect pests.
At the nursery, we are trying very hard to switch to organic methods to control pests and disease. At Bayou Bend Home and Gardens, home of the Ima Hogg plantation, the emphasis is on organic practices as well. Much of Bayou Bend was flooded for four days. The extensive camellia gardens were flooded along with the rest of the park. To start the revival process, the soil at the gardens was first attended to. Compost was added along with dried molasses and Microlife 6-2-4. Like the gardens at Bayou Bend, our gardens need to be replenished with organic matter after flood damage. Adding organic matter to your camellias and azaleas is the first line of defense against pests. Adding mycorrhizal fungi to your plants also helps the roots systems with the uptake of nutrients which is very important to the shrubs health.
The garden environment of your camellias and azaleas is critical to your plants health. Camellias need an acidic soil and partial sun to shade to be truly happy. Azaleas also need acidic soil. They need sun or shade depending on the type and need to be located accordingly. For example, encore azaleas prefer sun. Good organic matter, a proper soil pH and correct water and sun requirements go a long way in helping your plants fight pests and disease. Air circulation is also very important for your plants health. Prune your shrubs so they have an open habit allowing air to flow through the branches. A healthy plant is a strong plant and better able to fight insects.
The next step in warding off pests is vigilance. Keep a look out for insect pests when you water. During spring and summer do frequent checks on the undersides of your camellia leaves. You are looking for slightly fuzzy white and brown insects on the under side of your leaves. This is tea scale. The adult insects produce a hard shell, don’t move, and suck the juice out of your leaves. Tea scale can sometimes be misdiagnosed for a fungus because of its fuzzy appearance. At the first sign of scale, remove all the infected leaves and dispose of them away from you camellia. If scale is caught early you can control it by removing it. Female scale insects hatch eggs underneath their protective shell. Once the eggs hatch the crawlers emerge. Crawlers travel around the camellia until they settle down to feed. Once they have found a spot they stop moving and produce their own hard shell. Crawlers usually emerge in spring so spraying with a good horticultural oil will smother the insects. Once they have formed a hard shell they are much tougher to kill. Neem oil has been shown to be effective for controlling scale but must be reapplied throughout the growing season. D- limonene, the active ingredient in orange oil has also been tested on scale with some success. Both neem and orange oil have been shown to eventually break down the hard shell of the scale. All of the above mentioned methods for controlling scale are organic. These control methods take diligence and persistence by the gardener but the reward is no harmful chemicals in your garden.
Vigilance is also important to keep ahead of pests on your azaleas. Lace bug is the most common insect pest for azaleas in our area. Lace bug damage on azalea leaves will look like silvery white or yellow spots. The lace bugs themselves are very hard to see due to their almost translucent appearance. Lace bug, like tea scale, causes damage by sucking sections of the leaf dry. Also like tea scale, lace bug is found on the underside of the leaves. Control is much like tea scale control. Remove affected leaves and dispose of them away from the plant. Insecticidal soaps, neem oil or horticultural oil will also kill lacebug. When spraying these oils , make sure to cover both the tops and bottoms of the leaves to get all of the insects. Reapplication of oils or soap throughout the growing season will add an extra layer of protection. One caution on horticultural oils including neem oil, do not spray these oils in the heat of the day. They can burn your plants leaves.