Who would have imagined we would be talking about too much water in our landscapes in July in Texas? The record-breaking amount of rainfall we have received has actually ended our drought and filled up our lakes. This is wonderful, but it does bring with it a few horticultural issues.
Some of our soils in Denton County are clay, which is very slow-draining. Those of you with clay soils may not have experienced actual flooding in your yard, but your soil was very saturated with water. So saturated that air exchange for the roots of plants was limited or cut off. You may have even noticed a sewage-like smell in your yard; this is a sign of lack of oxygen in the soil.
Plant roots need water and oxygen. When air is restricted, plants will often show similar signs to drought stress such as wilting and leaf loss. Many plants and trees may shed their leaves and look dead. Some may just wilt and have yellowing leaves. What is occurring is that the plant is recovering from extreme stress and is going through a type of dormancy. We typically expect this to exhibit itself in what appears as a slow decline but then the plant seems to die overnight.
Now that we have been drying out, roots can recover and we may see that the plants and trees do recover. Recovery may be slow.
We don’t recommend fertilizing shrubs or trees at this time, as fertilizer can often add additional stress and will tax the root system. If you would like to do something for your shrubs and trees, add a layer of mulch. A mulch layer of 3 to 6 inches of chipped wood will also improve your soil over time by improving drainage and providing more organic material. Any mulch material will help buffer soil temperatures, reduce weed competition and reduce water loss, which will help reduce stress on your trees and shrubs. I don’t know what the rest of the summer has in store for us, but if we do get dry and hot later on, it may be that you will need to add supplemental irrigation to these trees and shrubs that have experienced this stress.
We are also seeing more disease problems because of the overcast weather and excess of rain. Fungus diseases are common when leaves stay wet for a while. Also they can easily spread on the plant by rain splashing fungus spores around. To help curtail the spread of fungus diseases, remove fallen symptomatic leaves from around the plants and perhaps do some selective pruning to improve the air circulation around the plant. The weather conditions also have increased some bacterial diseases that may be causing holes in leaves or other symptoms.
An interesting insect we are seeing a lot of right now is the bagworm. They feed on many different types of plants, but we tend to see them on arborvitae most frequently. The female bagworm is wingless and lives her whole life in the bag that she makes of silk and leaves. Bagworms hang from trees like defoliating little ornaments, oftentimes unnoticed until the trees are practically leafless. Bagworms are one of the few pests that can be effectively removed by hand. Because bagworms generally overwinter in the egg stage, every bag you remove in the winter holds the potential for hatching 500 to 1,000 eggs the next spring.
It can be difficult to know exactly what is ailing your plants — bacteria, fungus, insect or environmental conditions — and what to do about it.
Our office can assist you with that information, 940-349-2892 or email@example.com.
JANET LAMINACK is the horticulture county extension agent with Texas AgriLife Extension. She can be reached at 940-349-2883 or firstname.lastname@example.org.