Gene’s Summer Tips

Watering & Spraying in the Heat

When the thermometer shows temperatures are in the high 80’s and above, re-think your idea about going outside to do any watering and spraying of the lawn and garden. Sure, it’s probably not good for you to be outside in that heat, but applying water or liquids at that time is always bad news for plants.

Plants will take up most of their water needs in the cool early morning, so they will be full to the max to face the afternoon heat. So water then, before 10 am, and then check them around mid-afternoon to see how they are doing.

Putting water on plant foliage and grass blades in the heat of the day can concentrate heat high enough on the wet parts to cause tissue damage. Add water-soluble fertilizers or pesticides and see the damage increase. The purpose of early morning watering is so that the leaves will be dry by the time the heat starts to build up. Always avoid spraying weed killers during hot times of the day. The herbicide chemical become volatile in the heat, separates from the water, and can be carried some distances by the wind as vapor. When that vapor hits cool air, the herbicide condenses to a liquid and may “rain” on your neighbors favorite azaleas. So for many good reasons, “water or spray early in the day”.

Deep Watering Method

Apply water slow and deep to landscape plants, vegetable gardens and lawns. Plants of all kinds, whether they are planted in the ground or in containers, prefer to be watered only when needed and slowly and deeply. This method cuts down water usage and reduces the time spent in the watering task overall. If you have an installed drip irrigation system, use a soaker hose, or water by a hose-end sprinkler, this method applies to you.

Slow watering allows small amounts of water to be soaked up faster than large amounts applied all at one time. This means small amounts of water applied to the surface of the soil continually over a long period of time. What happens is that at the end of the time period of watering, the water has penetrated very deeply down into the soil, reaching and exceeding the level of the plants’ deepest roots.  Next, wait a relatively long time before watering again, even in hot weather.

The deep watering insures that all the root system down to the bottom roots are well-watered and not just the roots closest to the surface. This fact means three things. Deep watering insures that the entire root system is receiving water.  Deep watering means that there is an incentive for plants to send roots deeper to take advantage of the deeply-watered soil. Lastly, the water that goes deeper than the roots will rise up through the soil and water the roots later if the gardener does not apply any water to that same area for several days. The reason is that if the surface soil is allowed to dry out, capillary action will draw water upwards from below and that moisture will provide several days of water to the roots without applying more water from above.

Lawns in particular benefit greatly by this method of applying water to lawns. The University of Maryland Extension states that lawns in Maryland in summer should only need to be watered in once a week with one inch of water. How is this possible? First, you must know how much “one inch of water” is. This term refers to putting water on your lawn through a sprinkler or other lawn irrigation system. Let’s take a lawn sprinkler for example. Take the lawn sprinkler you intend to use when watering your lawn. Place it on the lawn and turn on the water faucet. Find and mark the farthest point at which the sprinkler water will reach on your lawn. Select three identical empty cans. Mark on the inside of each can with a line at the level of one inch from the bottom. Place one can at the farthest point where the sprinkler water could reach. Place another can half-way between the can you just put down and the sprinkler. Put the last can close to the sprinkler. Note the time on a watch. Turn on the water on. This is just like a rain gauge. When last can finally reaches the one-inch line, turn off the water and note the elapsed time. Whatever the time you get, that is the time that your sprinkle will put out one inch of water. You should water your lawn only once a week with the same sprinkler for that specific amount of time. You will find that you’ll be watering less frequently, thus using much less water

Kill Lawn Weeds Now Before Fall Seeding

Many tasks associated with lawn care are dependent on correct timing. One such task is killing existing weeds in the lawn prior to seeding that lawn in the fall. The timing is important for two reasons. First, the weed killers you would use are systemic in nature. That means that they must be applied to the green foliage of the target weeds so that the herbicide can be absorbed by the leaf blades and sent along the plant’s sap system to the roots. Once they reach the roots, the weed plant dies completely. This does not happen if the plant is not actively growing, so do it in summer for best results. 

The second point is that the herbicide (weed killer), whether in liquid form or dry granules, must remain on the surface of the weed leaves long enough to be absorbed. So don’t apply it when you expect rain within 4 to 6 hours. Finally, weed killers do not harm mature grass, but could harm young grass. Make sure you read the label of your herbicide to see how long you have to wait to apply grass seed after applying the product. Different herbicides have a waiting period of as little as 2 weeks to as long 4 weeks.

What Causes Sooty Mold on Crapemyrtles?

There is a common fungus that raise a lot of concern among home gardeners, not because it causes any significant plant damage, but it looks bad enough to imagine that it could. The leaves of hollies, camellias, crape myrtles, magnolias and many other shrubs and trees are seen covered with a thick layer of jet black “soot”, as if the plants had been downwind of a chimney billowing thick black smoke. This black layer of sooty material is formed by the fungi from the genera Capnodium, Fumago and Scorias. They are attracted to leaves and stems of plants by only one thing – “honeydew”. Honeydew is the sweet liquid excretion made by sap-feeding insects such as aphids, leafhoppers, mealybugs, psyllids, soft scales and whiteflies. These insects routinely spill large quantities of the ingested sap on to lower branches of the plant and on the ground. The sugary honeydew attracts many feeding life-forms, including ants, flies and the sooty molds. They will only stay around as long as the insects creating the honeydew are feeding and providing them their sweet food. To get rid of these honeydew producing insects, I would recommend applying the Bayer Advanced Shrub & Tree Feed and Protect for outdoor, in-ground shrubs and trees. For indoor plants and plants in containers, apply the Bonide Systemic Houseplant Insecticide.

The only direct harm the sooty mold may cause is to block sunlight to the green leaves which may disrupt the making of food (photosynthesis).

Alternating Fungicides

One of the practices that many seasoned gardeners follow is the alternating of fungicides when treating common plant diseases. Rose enthusiasts learned many years ago that the diseases common to roses seemed to eventually to regain the upper hand, even though they were using what they thought was the latest and best products on the market. The fungicides they used did a great job, but in time the diseases seemed to becoming immune to them. They soon learned the answer to this problem was to use the same fungicides, but not consistently, but alternately. Living organisms had the habit of adapting to the effects of chemicals, slowly developing a tolerance to those chemicals over time and exposure. Each new generation of disease organism became less and less susceptible to the chemical. They would use Daconil and make a note to switch to Copper Sulfate or Mancozeb when another spraying for the same pest was required. Doing this kept the disease off-balance, never exposing the disease to the same too frequently. This seemed to work quite well and I prescribe this practice even with a seemingly endless introduction of new chemical pesticides each year.

Summer Rose Care

If you have Knock Out, Hybrid Tea, Floribunda or climbing roses that have just finished blooming, it is a great opportunity to give them a light pruning and fertilizing. After blooming are the rest periods that roses use to recover from the energy drain during blooming and prepare for the next round of flowering. Some roses could use a trim and deadheading the of the spent rose blooms, which will help to redirect the plant’s energy to producing more flowers, not seeds. Roses can be fertilized at these rest breaks, as they could certainly put these added nutrients to good use.