July 14, 2016
During the month of June, we had many days of warm weather but the humidity level was very low. Low humidity means that on those warm and windy days we found that our plants would dry out quickly. The dry air would pull moisture out of the plants and it would pull moisture out of the ground too. As you know, we had a shortage of rainfall meaning that watering plants became practically a full time job at the garden center. Many of you would water your plants in the morning but by the time you go home in the late afternoon, you probably had to water again.
The only good news that came out of the dry air was that fungus diseases had very little chance of getting started in all of our gardens. Fungus diseases usually get started when we have moisture on the leaves of the plants in the late evening and very early morning hours. We have had some warm and humid weather in July. When the days are warm and humid, the lowering temperatures at night means that moisture in the air settles onto the leaves of the plants. Moisture on the leaves of your plants and cooler nighttime temperatures creates the perfect breeding ground for fungus diseases on your plants. You will find that if you water your plants late in the day and you get water on the leaves, you will be creating a perfect environment for the growth of fungus diseases. If you have an automatic sprinkler system that comes on at 2 AM to water your plants, the wet leaves during the rest of the night can be very prone to fungus diseases getting started on your plants. I always advise people who use a sprinkler system to have the system come on at 5 AM. Once the watering has stopped, the sun is rising and the leaves will begin to dry out. Just this small change in timing can really cut down on the conditions that favor the growth of fungus diseases.
There are different types of materials that are called fungicides. These are classified as preventative or curative fungicides. If you apply a preventative fungicide before the disease starts, you can, in many cases, prevent fungus diseases from happening on your plants. Human nature being what it is, most people don’t treat for fungus diseases until the disease shows up on the plants. At that point, preventative fungicides are not very effective at controlling the disease. Once a disease has started, you should be using a curative fungicide. This type of fungicide will stop a disease from spreading to uninfected leaves or it can stop a disease from getting started on adjacent plants in the garden.
I have always advised my customers and readers of this column to check their plants several times a week for signs of fungus diseases on plants. If you see black or brown spots on the leaves of your plants or if you see what looks like white powder on the leaves, you probably have the beginning of one of the fungus diseases attacking your plants. It is very important that you treat immediately to stop the disease from spreading to the rest of the plant and ultimately spreading to the rest of the plants in your containers or your gardens.
Summer is a season of warm and often humid weather. Many people enjoy this type of weather but your plants may not if they develop a fungus disease. During the months of July through September, you need to keep an eye on your plants and spray a preventative fungicide when conditions are favorable for the growth of plant diseases. If the disease gets a head start on you, then treat your plants with a curative fungicide.
Well, that’s all for this week. I’ll talk to you again next week.