Prepared by:
Dan Gill, Consumer Horticulture
LSU AgCenterTop
Wind Damage to Trees
Determining if Large Wind Damaged Trees Can be Salvaged
Wind Damage to Shrubs
Wind Damage to Herbaceous Plants
Flood Damage to Landscape Plantings
Food Crops
Flood Damage to Lawns
Loss of Shade Trees
LA One Call
Soil Testing
Wind Damage to Trees
Much of the work dealing with trees after a hurricane should be done by professionals who have the equipment and training to do the job safely. Most people do not have the equipment or expertise to safely remove large trees or fallen trunks. Also remember that downed power lines are often present around fallen trees, and take necessary precautions.
By law in Louisiana, the individual or company you hire to do tree work must be licensed by the Louisiana Department of Agriculture and Forestry and carry the proper insurance. Individuals and companies doing tree work should carry liability and workers comp insurance, and the LDAF does recommend you ask to see proof of insurance before hiring an individual or company. Carefully supervise any tree work being done, and do not pay for the work until it is done to your satisfaction. The LDAF will provide regulatory oversight of this work. Only licensed arborists or utility company personnel are to work on downed trees on utility lines.
Remove fallen trees as soon as it is practical (obviously, trees that fall on or near the house get top priority). If you want the stumps ground out, you need to check with the company removing the trees. The ground up wood left from the stump grinding (and also ground up branches) may be used as mulch in beds, to cover walkways or composted for use as a soil amendment during bed preparation.
Smaller trees and branches can be handled by homeowners with chainsaws. This may be necessary to clear pathways, driveways or remove branches around a home. It is critical that you understand the safe use of such equipment and follow manufacturer’s safety precautions carefully. Read user instructions thoroughly and do not attempt to tackle jobs that are beyond your ability to safely carry out.
Remove large branches that are broken but still hanging in the tree. These branches pose a significant risk as they can fall at any time. This should be taken care of as soon as possible. Less critical are broken stubs where branches were lost, however these stubs should eventually be pruned off to allow the trees to heal over the wounds. Make the final pruning cut just outside of the branch collar at the base of the branch when removing broken branches or stubs.
Remove older trees that are so badly damaged they cannot be saved or those that are significantly leaning. Unless a tree appears to be leaning so far that it poses a hazard of falling, these jobs can be put off.
Young trees planted within the past few years are often blown over by high winds or may be leaning. These trees, generally less than 10 inches in diameter and planted within about 7 years, should be saved. Straighten them as soon as possible and they will usually survive and recover. If the roots are exposed, cover them with soil or mulch to keep them moist until you get a chance to straighten the tree. Newly reset trees will need to be supported until they reestablish a strong, new root system. This can be done with stakes or guy lines depending on the size of the tree and the situation. Leave the support in place for about 9 to 12 months. Limited pruning may be done at the time of resetting to remove damaged branches and to lighten the weight of the canopy, but do not prune excessively. It is generally not practical to straighten larger, more mature trees that have blown over.
The high winds of strong hurricanes will strip the foliage from trees. Trees whose foliage has been stripped away are not dead despite their appearance, and they will usually recover. Do not immediately cut down trees whose foliage has been striped away by high winds. If they do not produce new growth the following spring, however, they should be removed. The winds may also damage the foliage without stripping it away. In this instance the foliage of the tree may appear unhealthy or brown. Again, damaged leaves will not kill a tree and you should wait until the next spring to determine whether or not the tree has survived.
Do not fertilize trees with nitrogen until the next year.
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Determining if Large Wind Damaged Trees Can be Salvaged
Many larger trees that receive wind damage but remain up right can be salvaged, depending on how much damage was done to the canopy and the species of the tree. Do not be concerned if the trees were stripped of foliage – it will grow back. Focus more on the damage done to the branch structure. Loss of or severe damage to most of the main branches likely means the tree should be removed. This would be particularly true for brittle wooded species such as pecan, pine, maple or hackberry. Trees that only lose secondary branches and few or no major branches can generally be pruned and saved.
Evaluating standing trees to determine if they need to be removed or can be saved is often best done by a knowledgeable individual. If you have difficulty determining which standing trees could be salvaged, contact a local licensed arborist to look over the trees and help you decide. There is no hurry to make these decisions. It is often advisable to wait until the next spring/summer to see how the tree grows out and recovers before making a final judgment.
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Wind Damage to Shrubs
Remove any debris that may be covering the shrubs, such as tree branches and debris from buildings, as soon as possible.
Taller shrubs may be partially blown over by high winds. If the roots were not exposed for long periods and the shrubs still look reasonably good, straighten them, cover their roots and stake them to hold them upright. Leave the stakes in place for 6 to 9 months. Trim any broken branches, but otherwise avoid extensive pruning of living branches.
The foliage of thin-leaved species may look burned. High winds blowing against the foliage can cause this type of damage. It is generally superficial. Extremely high winds can actually strip the foliage from shrubs. They are still alive and will usually recover should this happen. Wait until the following spring to determine if they will survive. Branches that do not leaf back out with the rest of the shrub are dead and should be pruned off. Shrubs that do not produce any new growth by the following spring should be removed.
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Wind Damage to Herbaceous Plants
Herbaceous, or non-woody, plants can be divided into two broad categories – annuals and perennials. Annuals are generally not worth salvaging if they received a lot of damage. Pull them up and compost them. Apply several inches of mulch to the areas where annuals were growing to prevent weed growth until you get time to replant.
Perennials will generally recover even if their foliage was shredded by the wind. Prune off badly damaged growth and give them time. They will usually resprout.
Banana plants are very large growing perennial herbaceous plants. Moderately high winds (50 to 70 mph) will shred the foliage but not greatly damage the plants. Just trim off the damaged foliage. Winds of 100 or more will blow over and shred all the top growth. Cut the banana plants back to the ground. They will resprout the next year.
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Flood Damage to Landscape Plantings
Flooding can involve freshwater or saltwater. Freshwater flooding is generally caused by excessive rainfall, while saltwater flooding is limited to coastal areas and is caused by storm surges associated with hurricanes.
Freshwater flooding primarily impacts landscape plants by saturating the soil. Plant roots derive oxygen from air spaces in the soil, and when these spaces are filled with water roots are deprived of the oxygen they need. Initially, the roots stop functioning properly. When the bright sun comes out after a period of excessive rain, it is not unusual for plants to wilt. It is odd to see plants wilting in soil saturated with water, but it makes sense. Roots will not function properly if they do not get oxygen, and saturated soils are low in oxygen. So, the roots quit absorbing water, causing the plants to wilt. Root rot follows if the situation persists. Root rot is the greatest danger to landscape plants during flooding. The longer the soil stays saturated the more damage that occurs.
Saltwater flooding is due to the storm surge that accompanies hurricanes, and will primarily affect areas close to the coast. Saltwater from the Gulf of Mexico is pushed onto land by the storm surge. Saltwater flooding also affects plants by saturating the soil, but the salt in saltwater poses an additional problem. High salt levels are damaging to many plant species. Where saltwater flooding has occurred, irrigate the plants generously with fresh water to dilute the salt and leach it deeper into the soil away from the root zone. If rains saturate the soil before the salt water flooding occurs, the salt water is less likely to penetrate and contaminate the soil. If desired, soils can be tested for salt levels through your local LSU AgCenter Extension office.
Flood waters also carry silt and debris. These materials are deposited on lower growing plants, such as shrubs, ground covers, annuals and perennials. It is important to remove these materials as soon as possible. Use a rake to remove most of the larger material, and then a hose with a nozzle attached to wash off the remainder.
After the flood waters recede, remove all mulches from around shrubs and in beds for a few weeks to allow the soil to dry out more rapidly, and then replace it. Use a garden fork to help speed drying of soil in beds. Insert the fork tines straight into the ground to a depth of six to eight inches, gently rock back and forth and then pull them straight out. Do not dig with the fork. Repeat this throughout the bed spaced about every 10 inches.
Do not immediately fertilize trees, shrubs or ground covers after a flood event in late summer or fall. Wait until the next year.
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Food Crops
Do not consume any fruit from fruit trees, vegetables or herbs that were or could have been touched by flood waters. You may, however, usually eat fruit the trees produce in the future. You can also generally eat the new growth of herbs and vegetables produced after the flood waters recede.
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Flood Damage to Lawns
Remove heavy debris and silt that may have been deposited by flood waters on your lawn as soon as possible. Use a rake to remove most of the larger material, and then a hose with a nozzle attached to wash off the remaining mud.
The surge of salt water brought inland by a hurricane can cause a lot of damage to turfgrasses in lawns, golf courses, parks and playgrounds. Thoroughly watering the grass as soon as possible with clean, fresh water is probably the most important thing to do. This will help rinse salts from turf leaf surfaces and leach salts (which can damage roots) from the grass root zone. Raise the mower’s cutting height a notch to help the turf regenerate a stronger root system. Bermuda, zoysia and St. Augustine have good salinity tolerance.
If the lawn survives, do not fertilize immediately after a flood that occurs in late summer or fall. Wait until April the next year to put out lawn fertilizer.
It is likely that lawns that stay flooded for an extended period will be severely damaged or killed (bermudagrass is the one most likely to survive extended flooding). If the entire lawn needs to be replaced or bare areas occur and the soil needs to be stabilized to prevent erosion, turf sod can be laid through the fall. Dormant sodding could be done during the winter. Another option is to plant the area with ryegrass. Ryegrass will grow through the winter and will stabilize the soil until a new permanent lawn can be planted in spring. Ryegrass will need to be mowed occasionally through the winter. In April or May a new lawn can be established or repairs to an existing lawn can be made using sod, plugs or seed.
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Loss of Shade Trees
One of the greatest landscape losses during hurricanes is mature shade trees. It takes decades for shade trees to achieve their mature size, so they cannot be quickly replaced. Large trees create shady conditions in landscapes and largely determine what kind of plants can be grown. Areas shaded by trees are planted with plants that prefer and thrive in shade.
When large trees are blown over and removed, areas that were previously shaded will receive substantially more sun. Suddenly exposing plants that were shaded to full sun will burn or scorch their foliage. Some plants will adapt and the new growth they produce in the sunnier conditions will do well. Most shade-loving plants, however, will not do well in the sunnier conditions. These plants should be transplanted to areas of the landscape that are still shady, and sun-loving plants should be planted in their place.
When choosing a replacement tree, do not simply focus on rate of growth. People always want a tree that will grow as fast as possible to replace the lost tree. It is also very important to look at the appropriate mature size and whether the tree needs to be evergreen or deciduous. Ornamental features should also be considered such as flowers, attractive berries, brightly colored fall foliage or unusual bark. Be sure to choose trees that are well adapted to your local growing conditions and soil type.
Even fast growing tree species will take at least five years to begin to create much shade.
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LA One Call
If you will be doing any digging during your recovery efforts, you should contact LA One Call to make sure you do not damage underground utility lines, such as water, sewer, gas, electricity or phone. Call 1-800-272-3020 forty-eight hours before you intend to dig. When the lines have been marked, dig with care and respect the marks.
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Soil Testing
You may want to have the soil in your landscape tested if the flood water covering your yard was polluted, brackish or salty. Vegetable garden beds, in particular, should be tested. This can be done through the LSU AgCenter Soil Testing and Plant Analysis Laboratory in Baton Rouge. Check with your local LSU AgCenter Extension office for information on how to take and submit samples in your parish, and to receive a carton to submit your sample in and the form that must accompany it. Once you receive the results, you can contact your local LSU AgCenter Extension office and discuss them with the county agent.
The routine soil test costs $7 per sample and will tell you the texture of the soil, the soil pH, sodium level and the level of several essential elements plants need, including phosphorus, potassium, magnesium, calcium, sulfur, copper and zinc.
Where the flood water was brackish or salty, you want to pay attention to the sodium level in the report. Levels under 120 ppm should pose no problem for most plants. If your soil test indicates that the sodium level is “Excessive” contact your county agent. They can help determine, based on other soil characteristics, whether or not the sodium level actually needs to be reduced. Higher levels of sodium can be reduced with the application of gypsum and leaching by rain and irrigation.
You should also consider having the soil tested for soluble salts ($4/sample). High soluble salts can damage plants. Levels lower than 350 ppm should not be a problem. High soluble salts levels can be reduced by leaching the soil in a bed with copious amounts of fresh water.
Where pollution is an issue, the LSU AgCenter Soil Testing and Plant Analysis Laboratory can test for some materials that may have been in the flood water. Two tests in particular would be useful to test for heavy metals or oil: 1) Zinc, Arsenic, Cadmium, Lead ($4/sample) and 2) Oil ($4/sample). What is important is not necessarily what was in the flood waters, but how much of these substances get into the soil and whether they will affect plant growth or producing edible crops.
The only way you can know for sure what effect the flood waters had on your soils is if you had your soil tested previously. Then you could compare an old soil test to a test done after the flood. For instance, lead levels in urban soils are often high before floods due to the use of lead based paints and leaded gasoline in the past. Lead is not toxic to plants and is primarily a concern in beds used for growing vegetables.
In situations where the existing soil is contaminated to the point that it is no longer suitable for the plants you want to grow, raised beds can be built and filled with a blended soil mix available from local soil companies whose products were not affected by the flood or river sand amended with organic matter.
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