Weeds are opportunistic, and when Hurricane Katrina damaged or destroyed much of south Mississippi, weeds were given the opportunity to thrive. John Byrd, weed specialist with the Mississippi State University Extension Service, said the wind, the storm surge and cleanup efforts allowed weeds to gain ground.
“Weeds enter in the voids where other vegetation was growing,” Byrd said. “You hope the weeds that come up are native plants, but a number of introduced plants can spring up. Because they have no natural enemies, they can thrive.”
Byrd said cogongrass is a highly invasive, non-native plant that could use the opportunity created by Katrina to spread significantly. Cogongrass disperses seeds in the spring, and with many areas laid bare by storm damage, cogongrass has numerous opportunities to move into new areas.
Wind has a greater effect on tall bushes and trees with mass further off the ground than it does on lower plants. When wind damages or destroys the trees forming canopies in forests or in yards, weeds can invade the new environment.
The storm surge brought salt water to many square miles of land, and in some areas, deposited sludge with a high salt content. Byrd said the equipment used to clear debris after the storm can further damage the landscape, create new voids for weeds to invade and spread plant species.
“As equipment moves from one location to another, unless someone takes the time to clean the seeds, rhizomes and tubers off the equipment, it can deposit this plant material at the next site, carrying weeds to a new location,” Byrd said.
Mike Steede, George County Extension director, said post-Katrina weeds are not an issue with pastures as they did not suffer directly from wind or storm surge damage, but debris on the ground and drought after the hurricane hurt them.
“We have a shortage of grass for our cattle producers,” Steede said. “After the storm, we had practically no rain for more than two months. That knocked out our fall hay crop.”
Wind took the roofs off many barns, destroying much or all of the hay stored inside. Cattle won't be able to start grazing pastures until mid-February at best, so producers are still struggling to get hay for the cattle while they continue to remove downed trees and replace destroyed fences.
“Because hay is so short and cattle prices are really good, I've been encouraging producers to look hard at their herds and cull,” Steede said. “If you have marginal cows, now is the time to get rid of them and get them off your feed bill.”
Kerry Johnson, Extension area horticulture agent, said landowners probably won't know until April if their turf has been damaged by salt water. However, if storm surge sludge was deposited, it should be removed from yards due to its high salt content.
“So far, we don't have documentation of widespread, excessive saline levels affecting turf,” Johnson said. “Grass should start greening up by early April. By that time, many homeowners likely will have their houses in order and will be ready to tend to their yards.”
Johnson said he is optimistic that most lawns were undamaged by exposure to salt water. If the lawn was flooded, collect samples for a soil test to determine if high levels of salt were deposited.
If the soil test shows elevated levels, Johnson said winter rains would be very beneficial. Test the soil again in mid-April to monitor salt levels before replanting damaged turf.
“Rain is the best treatment,” Johnson said. “In some cases, lime or gypsum applications may be recommended. In severe cases, storm surge sludge should be removed before new sod is laid.”
Johnson said unless damaged or destroyed by the force of water or debris in the water during the storm surge, bushes and other plants in the landscape should escape salt damage, too.
Salt deposited on plants may burn leaves and defoliate the plant for a time, but Johnson said no evidence yet indicates there will be widespread, long-term damage to landscape plants from brief exposure to salt water.
Bonnie Coblentz writes for Mississippi State University Ag Communications.