WSU Extension -Managing weeds after a flood.

Pastures after a flood need some special TLC. First and foremost, remove any debris, especially along fence lines and in corners. Livestock could be injured by barbed wire or sharp metal, glass and garbage. Removed any fallen wild cherry, laurel, plum or peach tree limbs from pastures to prevent poisoning. Do not feed livestock any silage that has been flooded. Horses, sheep, poultry, swine and cattle are effected most severely in that order from damaged feed. Lack of adequate forage could force livestock to eat poisonous plants that they would otherwise avoid.

This winter's flooding has had an effect on weeds we will be seeing next spring and summer. Many weed seeds float and moved great distances in floodwaters. Existing ground cover, whether it is lawn, pasture grass or native perennials damaged by flooding will be less able to compete with weed invasions.

Pastures and lawns that have been submerged for less than seven to 10 days and are covered in less than three inches of silt have a good chance at complete recovery. Lower temperatures and the stage of growth during winter are also good indicators of a speedy recovery. Perennial ryegrass and tall fescue are both excellent grass species for flood survival. To speed the process of recovery break up any silt crust as soon as possible with a rake, harrow or mechanical aerator; test the soils for nutrients like lime, phosphorous and potassium; apply nitrogen fertilizer or manure after danger of further flooding has passed and over-seed thin areas with a desirable permanent seed mixture.

Pesticide storage in flood prone areas is a major concern. If you suspect pesticide contamination due to flooded outbuildings, even garden sheds, let caution guide your every move. Before entering an area suspected of a spill, wear protective gear, especially safety boots. Any pesticide spills should be reported to the Department of Ecology, SW regional office at 360-407-6300 in Olympia for advice on what to do to prevent ground water contamination, including your well. Pesticides should be stored in a safe location, not likely to flood and far from well heads and play areas. Don't store large quantities of pesticides, purchase only enough for a single season to avoid disaster.

During the next growing season, new weed species may appear where floodwaters deposited seeds. Extra monitoring for weed invasions during the growing season will literally nip those unwanted plants in the bud. If in doubt as to the identity of new plants appearing on your flood damaged property, contact your county WSU extension.