Growing strawberries on plastic or other types of mulch keeps the berries clean and helps prevent weed growth. (Photo by Kiki Fontenot, LSU AgCenter)

News Release Distributed 12/03/15

BATON ROUGE, La. – December marks the start of the strawberry harvest season in Louisiana.

“Louisiana strawberries are delicious whether produced on a Louisiana farm or in your backyard,” said LSU AgCenter fruit and vegetable specialist Kiki Fontenot. “Fresh-picked berries that have fully ripened on the bush are amazing.”

Strawberries are typically planted between the end of September through mid-November, and weeds can be a constant problem. Even if the berries already are planted, growers still have plenty of time to initiate a good weed management plan, she said.

Strawberries are adaptable to containers, raised beds and in-ground gardens, and home gardeners need to start with a clean bed. If you’re growing strawberries at home, knowing your weed management options is essential, Fontenot says.

No matter where they’re planted, remove all weeds from the location prior to planting berries. And once the weeds are removed, apply mulch.

“Mulches not only prevent a majority of weeds from emerging, but they also provide a barrier between the berries and the soil,” she said.

If you have applied a thick-enough mulch layer, hand pulling weeds shouldn’t be too big of a chore. Mulch does more than hold down weeds; it also keeps the fruit off bare ground. “Fruit that develops in contact with soil will rot,” Fontenot said.

Gardeners with small plots have several mulch options, Fontenot said. Black plastic mulch sold at specialty hardware stores is very effective in both keeping berries clean and preventing weed infestation. Other choices include leaves, pine straw and shredded newspaper.

“In any of these cases, apply at least a 4-inch-thick layer,” she said. Extra-thick layers of pine straw are also beneficial because they can be raked over plants when temperatures drop below freezing to provide a degree or two of protection.

“Many gardeners also claim that raking pine needles over red berries helps camouflage the near-ripe fruit from garden thieves such as birds and squirrels,” she said.

A few gardeners might insist on using herbicides, Fontenot said. Herbicides labeled for use in and around strawberries, however, are limited for gardeners who don’t have a pesticide handler’s license.

Preemergent herbicides are those that are applied before weeds appear.

Corn gluten meal packaged and sold by Preen is one of the only preemergent herbicides available to home gardeners. This product is organically labelled but cannot be applied before planting. Strawberry plants must be established in the garden for about three weeks or until they’re at least 3 inches tall. Then simply shake the corn gluten meal around – but not on – the plants.

Once weeds break through the initial barrier of mulch and preemergent herbicide, gardeners have two chemical options for killing weeds.

Grasses can be controlled by spraying sethoxydim, the active ingredient in Poast and several other trade-name herbicides. Sethoxydim is a selective herbicide that only kills grasses. Applying sethoxydim over the top of the plants will not injure the berries.

If you have both grasses and broadleaf weeds emerging in your strawberry patch, you can apply pelargonic acid, sold primarily as Scythe, Fontenot said. This is an organic herbicide labelled for strawberry gardens. It is a burndown herbicide that will knock back annual weeds but require several applications to kill perennial weeds.

Because pelargonic acid is non-selective, it will kill or injure both broadleaf and grass plants – including strawberries. “Be very careful not to spray it on the berry plants,” Fontenot said. “Rather, use it in the row middles or around plants.”

“Enjoy growing berries,” Fontenot said. “And remember, weed control is important not only to keep your garden looking good but also to increase garden success. Weeds rob valued plants of water, nutrients and sunlight. Keep the weeds out, and your yields are sure to rise.”