Institute of Food and Agricultural Sciences
Hendry County Horticulture News
Plant Diseases Favored by Wet Weather
While October is generally considered to mark the official beginning of cooler drier weather locally, it is anything but dry this year. In fact, conditions have been positively soggy across the area, since our close encounter with Tropical Storm Harvey and subsequent downpours, which have dumped between 10 and 20 inches of rain in as many days. An over abundance of precipitation has filled aquifers to over flowing and has resulted in flooding conditions in many areas. One does not have to go very far these days to find what would normally be dry land covered with extensive sheets of water.
Although gardeners normally welcome rain, it is possible to have too much of a good thing. Excessive moisture can cause a number of problems for gardeners. Most diseases caused bacterial and fungal pathogens require free moisture to be present on leaves and other plant parts for several hours in order to become active and successfully attack their plant hosts. Such conditions have persisted more or less continuously for the past few weeks resulting in a surge in disease problems on ornamental plantings.
Since most plant diseases can not be cured but only controlled once a plant is infected, early detection and prevention is the key to managing plant diseases in the home landscape. Plant diseases typically manifest themselves by producing abnormal plant growth. Sick plants often produce one or more of the following symptoms, stunting, spots on leaves, stems or fruits, discoloration of plant parts, decay or rots on leaves stems, or fruits, wilting, and/or rapid death and collapse of entire plants or plant parts.
By learning to recognize these symptoms and monitoring plantings regularly, it is frequently possible to take steps to control diseases and prevent them from becoming major catastrophes. There are a number of fungicides that can be used to help control plant disease. In general, these are best applied prior to or early in the development of diseases. Since it is known that warm wet conditions are favorable for disease development, fungicides are most effective when applied on a preventative basis when environmental conditions favor the development of disease.
In addition to chemical means, a number of non chemical techniques can be employed to help prevent plant diseases in the home garden. Healthy plants are generally more resistant to disease than unhealthy or stressed plants. Attention to site selection and plant adaptation is important - a plant native to a dry area is likely to succumb to disease if planted in a wet site and vice versa. Proper fertilization and water management is also critical in maintaining healthy plants.
Wherever possible disease resistant varieties should be used. Pruning and staking can help improve aeration around plant foliage reducing the time that leaves and stems remain wet after rainfall or on foggy or dewy mornings. Many diseases can be easily spread from plant to plant when leaves are wet so it is important to avoid handling plants for any reason such as pruning or harvesting until they have dried off.
The initial stages of some infections can often be nipped in the bud so to speak by pruning of the affected part of the plant before it can spread. When employing this technique, it is important to remember to sanitize pruners before moving to another plant to avoid spreading diseases from one plant to another. It is also important to dispose of infected parts by burning or bagging to remove potential disease innoculum from the environment.
In wet areas, planting on raised beds or mounds and improving drainage where possible can also be effective tools in combating plant diseases. Where drainage is not possible, use of species adapted to wet sites can help avoid many problems
For additional tips on controlling plant diseases and for specific chemical control recommendations, please feel free to contact the Hendry County Extension Office. The knowledgeable gardener can avoid many potential disease problems and have a more productive and satisfying gardening experience by incorporating a number of disease control strategies into the home landscape. Good luck and good gardening.
Gene McAvoy is the horticulture agent with the Hendry County Extension Service. Direct your horticulture questions to PO Box 68, LaBelle, FL 33975, e-mail - email@example.com or phone 863-674-4092 or 863-983-1598. You are also welcome to visit the Hendry County Extension Office at 225 Pratt Blvd., LaBelle. Office hours are from 8:00 - 5:00.
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