Gold Coast Gardener

August 27, 2006

By Gene Joyner, Extension Agent
Palm Beach County Cooperative Extension Service

One of the most frustrating things to an individual is to look out at a beautiful plant that had been doing well and suddenly notice various problems occurring. Often it might be leaves turning brown and falling off or stems drying up and occasionally even the entire plant withering up and dying.

These are all symptoms of various diseases and during the summer months plant diseases are on the increase because most spread easily at high temperatures which are common plus they need sufficient moisture levels which frequent rainfall supplies.

Smaller plants of course often have more problems with disease than larger ones, but if you live in areas that summer rains cause high water tables or actual puddles to form around plants in the landscape that don’t dry up for several days, plants can get diseases and injury from this situation.

When we get high nighttime temperatures and frequent rainfall sometimes plant leaves may go for days without completely drying out and this is the high risk for plant disease invasion. Diseases are constantly found in the atmosphere and spores that land on leaves from fungus can enter through cuts, wounds, or even natural openings. Also sometimes simple things such as pruning cuts if they are wet and moist can have disease organisms land on them and begin to grow. Often bacterial galls can be seen at the site of former pruning or other wounds in the plant.

Diseases in plants because they are so variable are difficult to control with a single product. Most diseases in plants are caused by fungus and bacteria and viruses are a little bit more uncommon. Most of the plant diseases are fungus related and the fungus can be either spread through the air or by splashing water or can be soil borne.

Specific knowledge of the type of fungus is important to use correct control products. This requires a laboratory diagnosis at a plant disease lab and then you have to buy the appropriate material and apply it correctly. For that reason and the cost involved with plant disease analysis many people simply ignore the problem hoping it will go away on it’s own.
In some cases if we get dry conditions the problem may stop. Other times pruning out infected portions of the plant and removing it is another way of slowing down the progression of the problem.

Keeping plants healthy is another means of combating the diseases since healthy plants generally have fewer problems with diseases or if they are infected they make a more rapid recovery. People that tend to abuse their landscape and don’t fertilize or care for the plants properly suffer the worst damage as opposed to people who pride themselves on keeping their landscape in good condition.

Many plants also are available that are highly resistant to diseases, particularly many of our native plants. If you use those predominantly in the landscape you won’t run as high a risk of having disease problems develop.

Local neighborhood experience will also help you with disease problems and if your neighbors have problems with certain plants on a regular basis then that might be one plant you might possibly not want to include in your landscape.

Local nurserymen are also good sources of information on plants that can be used that have a high resistance to diseases or other problems.

If you want advice on plant diseases in the landscape and solutions for their control, contact the Palm Beach County Extension office and talk to one of the master gardeners or agents. Dial 233-1750 in the north and central county area or 276-1260 in the south county area.