Groundwork column for Dec. 16, 2012

Attack brown patch disease

Brown patch disease can come and go throughout the winter if the weather is mild. Treatment with fungicides containing myclobutanil, propiconazole, pyraclostrobin, thiophanate-methyl and triticonazole will reduce the spread of brown patch.

In addition, azoxystrobin is now available as granular fungicide. Azoxystrobin is one of the best fungicides on the disease.

Damage from brown patch will slow spring green-up and affected areas will remain unsightly until warmer spring weather conditions help with turfgrass recovery. Lawns may show signs of green-up in late February.

Do not push turfgrass growth with fertilizer at that time. Fertilizer applied too early will feed winter weeds and will result in lush turfgrass growth that is more susceptible to injury from late frosts and brown patch disease. Lawns may be fertilized late March to mid-April.

Plant protection

Protect plants from freezing weather. Tender shrubs can be covered with blankets for several days. Weight covers to the ground so heat released from the soil can’t escape on cold nights.

Moisture levels of the soil prior to, and during, hard freezes do a lot toward determining the extent of damage that may be done. Thoroughly water landscape plants before a freeze if the soil is dry. Strong, dry winds may cause damage by drying plants out and watering helps to prevent it. Dry plants usually suffer far more damage. Water three to four days prior to a predicted freeze.

Move all tender plants in containers and hanging baskets into buildings where the temperature will stay above freezing.

If this is not possible, group all container plants in a protected area (like the inside corner of a covered patio) and cover them with old sheets, blankets, quilts or frost cloth. It is critical that the cover extends to the ground and that it is weighted down with bricks to prevent wind from blowing under the cover.

When growing in containers, even hardy plants become more susceptible to freezing temperatures because their roots do not have the benefit of the warmth that radiates from the ground. Wrapping individual pots will help but only if the insulating wrap remains dry.

Frost cloth, also sold as floating row cover and frost blankets, is available at garden retailers and online. This lightweight material is used to prevent wind damage and tissue desiccation. It permits light, water and air to get to the plant yet retains soil warmth and solar heat.

Also sold as bags to cover plants and pots, this fabric increases daytime temperatures and moderates nighttime temperatures. And best of all, it is reusable and requires no laundering after use.

For plants growing in the ground, mulch with a loose, dry material such as pine needles or tree leaves.

Mulches will only protect what they cover and are best used to protect below-ground parts and crowns or they may be used to completely cover low-growing plants (to a depth of 4 to 6 inches). But don’t leave a complete cover of mulch on for more than three or four days.

Mulching tender perennials and tropicals is the best way to assure plant livability for next year. If the plant is special, dig it up and protect or take cuttings and root indoors.

Smaller individual plants can be protected by covering them with various sizes of cardboard or plastic foam boxes or ice chests.

Larger plants can be protected by creating a simple structure and covering it with sheets, quilts or plastic. The structure holds the covering off the foliage, preventing branch breakage and improving cold protection.

It doesn’t need to be anything more elaborate than three stakes slightly taller than the plant driven into the ground. The cover should extend to the ground and be sealed with soil, stones or bricks.

Plastic covers should be vented or removed on sunny, warm days. If plastic is not removed on sunny days, the temperature will quickly rise to dangerous levels and can cause more severe damage than had the plant been exposed to freezing temperatures.

For severe freezes, when temperatures dip into the teens, providing a heat source under the covering helps. A safe, easy way to do this is to generously wrap or drape the plant with small outdoor Christmas lights.

The lights provide heat but do not get hot enough to burn the plant or cover.

An incandescent light bulb can be used but carefully place it so the heat it produces does not damage the trunk, stems or leaves. Use only outdoor extension cords and sockets, and plug into a ground-fault interrupted (GFI) outlet. If necessary, a large plant can be pruned to make its size more practical to cover.

After the danger of cold has passed, unless plants are being kept inside for the rest of the winter, move them back to their spots outside where they can get sunlight.

For plants that are covered, remove or vent clear plastic covers to prevent excessive heat buildup if the next day is sunny and mild. Plants can be left covered with blankets or sheets for several days without harming them, but the covers eventually will need to be removed so the plants can receive light.

Do not prune anything right after a freeze. It often takes several days to weeks, even months, for all of the damage to become evident.

Damaged growth on herbaceous or nonwoody plants like cannas, elephant ears, birds-of-paradise, begonias, impatiens, philodendron and gingers may be pruned back to living tissue. This pruning is optional and is done more to neaten things up than to benefit the plants.

If the damaged tissue is oozy, mushy, slimy and foul smelling, however, it should be removed.

Generally, it’s a good idea to delay hard pruning of woody tropical plants — such as hibiscus, tibouchina, angel’s trumpet, croton, ixora, schefflera, copper plant and rubber tree — until new growth begins during the spring and it can be more accurately determined which parts are alive and which are dead.

Wait to prune hardy woody plants and citrus trees at least until spring green-up. Sometimes freeze damage is not immediately evident so waiting even longer, to May and June, is recommended.

Protect exposed faucets with foam insulating caps sold at hardware stores and home improvement centers. Protect water pipes with foam insulation tubing. To assure water flow, first wrap a heating cable around the pipe that supplies water to the home.

Drain water from above-ground pumps used for ponds and waterfalls.

Drain water out of garden hoses and sprinklers. Water expands as it freezes, and in so doing, it can rupture plastic and soft metal sprinkler parts. Hoses become brittle and must not be moved until all of the ice has melted again.

Got a gardening question? Write to Bob Souvestre, horticulturist with the LSU AgCenter, at Burden Center, 4560 Essen Lane, Baton Rouge, LA 70809, or email to bsouvestre@agcenter.lsu.edu, or call Master Gardeners at (225) 763-3990.