It seems we have feast or famine with rain here in North Florida. Too much rain and irrigation can be just as damaging as too little rain and irrigation for many tree species.
Food source issues
Dry weather has many hidden, long-term effects on trees. A primary effect is the disruption to a tree's food supply. Food for a tree is sugar produced by the leaves. Drought causes stored food to be used just to maintain living tree parts rather than for growth. Drought keeps trees from producing or storing new food for next year.
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In trees, food production, food storage and growth must occur every year to get the tree through winter and restart it in spring. Trees must save a large amount of food to be alive next year.
Drought can keep many trees from producing much food. During drought, little food is stored and little is used for new growth. Trees store most of their food in the last few annual growth rings. The thinner the growth layers from lack of food, the less area available to store food. In this situation trees are essentially "shrinking" to survive.
Recovery time extended
Trees require several good growing seasons to recover from one bad year. Tree species like oak, hickory, elm, ash and pine will need three to four good years to make up for one year of severe drought. Trees like maple, dogwood, beech, magnolia, sweetgum, yellow poplar and sycamore will need two to three years to recover.
Proper tree care can help trees live. Tree care is just as important in years following a drought as during the drought year itself.
Pests and diseases
Drought-weakened trees are the favorite prey for a host of pests. Many of these pests are only seen in abundance after a bad drought year. A weakened and declining tree is a great meal for tree pests like vascular diseases, woodborers, bark beetles, root rots and scale insects.
Care for drought-damaged trees involves light fertilization and plenty of water. Always use a soil test to determine fertilizer needs. Large doses of nitrogen when other elements and food are lacking can damage your trees. High nitrogen fertilizer can result in more shoot and leaf growth than the tree can support.
Good care also includes proper removal of dead wood to minimize falling branches and liability risks. Pruning of living branches on severely stressed trees should be delayed until next year. Keep a close watch on your trees for pest problems.
More information on tree selection and care is available from the UF/IFAS Extension Office in your County. An Equal Opportunity Institution
This article originally appeared on Northwest Florida Daily News: Dry weather damages trees. How to care for them? | Gardening