Hello Gardeners,A lot of calls have been coming into the Lafayette Parish LSU AgCenter office regarding various landscape/gardening topics and I thought I’d share them with Master Gardeners this month.
Many questions and comments address knockout roses which seem to be providing gardeners with a spectacular display of lush green foliage and gorgeous blooms. I contacted Dr. Allen Owings at the Hammond Research Station and he is witnessing the same performance from knockout roses. He feels that, because of our long winter with below average temperatures, knockout roses went through a longer and more complete rest period. When they finally came alive, they were rejuvenated. The results are seen in the foliage and flowers being more concentrated, instead of like in mild winters. Where the rest period is shorter and less complete, folage and bloom activity is spread over a longer period of time. As we say, Mother Nature did us a favor. Let us enjoy this spectacular display from reinvigorated knockout roses. Keep in mind, however, that as temperatures rise and place more stress on all roses, they will probably not look as spectacular.
On Cannas and Amaryllis, as we move into May and peak blooming declines, both will be developing seed pods. It is recommended that these seed pods be removed. Removing the seed pods allows the plant to redirect its energy to leaves and roots instead of wasting effort on seed development. Also, watch for damage from the canna leaf roller which is a caterpillar that causes brown deformed leaves and holes in the leaves of cannas. In some cases, weekly application of Orthene (acephate) will be needed to control damage from this pest.
Removing faded blooms from annuals bedding plants — commonly referred to as “deadheading” — also redirects the energy of the plants from seed development to bloom development. So to encourage extended blooming on annuals, remove blooms as they begin to fade.
The month of May is going to bring higher temperatures and cause the decline of many of our cool season annuals such as petunias, violas, pansies, and dianthus. As the temperatures progressively rise, begin making preparations to clean out these cool season annuals beds and replace them with warm season annuals such as ageratum, lantana, marigold, butterfly pentas, periwinkle, rudbeckia, salvia, dusty miller, cosmos, celosia — just to name a few. The more heat-tolerant petunias may persist into June or July, but with the more intense heat expect cool season plants to gradually decline.
If you notice the leaves of azaleas showing whitish spots or discoloration on the leaf surface, look underneath. If there are dark brown spots this indicates the presences of azalea lace bugs. This may require a couple of applications of an insecticide such as Orthene (acephate).
June bugs have been sighted for several weeks and are currently eating the foliage of several landscape plants including pecan trees. These brown beetle like bugs feed primarily at night because they remain in the soil during the day and emerges after dark. Sevin or any insecticide containing carbaryl as its active ingredient can be applied to plants being affected by June bugs/beetles just before dark, by the next morning it’s not uncommon to find these beetle bugs dead on the soil.
Removing faded blooms from annuals bedding plants — commonly referred to as “deadheading” — also redirects the energy of the plants from seed development to bloom development. So to encourage extended blooming on annuals, remove blooms as they begin to fade.
The month of May is going to bring higher temperatures and cause the decline of many of our cool season annuals such as petunias, violas, pansies, and dianthus. As the temperatures progressively rise, begin making preparations to clean out these cool season annuals beds and replace them with warm season annuals such as ageratum, lantana, marigold, butterfly pentas, periwinkle, rudbeckia, salvia, dusty miller, cosmos, celosia — just to name a few. The more heat-tolerant petunias may persist into June or July, but with the more intense heat expect cool season plants to gradually decline.
If you notice the leaves of azaleas showing whitish spots or discoloration on the leaf surface, look underneath. If there are dark brown spots this indicates the presences of azalea lace bugs. This may require a couple of applications of an insecticide such as Orthene (acephate).
June bugs have been sighted for several weeks and are currently eating the foliage of several landscape plants including pecan trees. These brown beetle like bugs feed primarily at night because they remain in the soil during the day and emerges after dark. Sevin or any insecticide containing carbaryl as its active ingredient can be applied to plants being affected by June bugs/beetles just before dark, by the next morning it’s not uncommon to find these beetle bugs dead on the soil.
Buck Moth Caterpillars Buck moth caterpillars are being reported by gardeners all over Lafayette and surrounding parishes. These black caterpillars covered with spines can inflict painful stings if they come in contact with your skin while you are gardening. If you’re careful to avoid them, spraying an insecticide may not be necessary as they will be gone as soon as they complete their life cycle. However if you feel the need to control them, any common garden insecticides such a malathion, sevin, bifenthrin, cyfluthrin , will give good control.
On woody plants such as citrus, figs and many of our woody tropical plants, damage that was done by this winter’s freezing temperatures has become more evident. By now, you can look at plants and visually determine what parts of these plants can be pruned based on new growth. Brown areas can be pruned/remove up to healthy green growth.
Several callers have asked about reddish discoloration on amaryllis leaves. The reddish discoloration is cause by a fungus disease called red blotch which is common on amaryllis. According to Dan Gill, the most appropriate practice is to remove affected leaves if the infection is severe.
Finally, numerous St Augustine lawns suffered some cold damage from this past winter. Most people don’t realize that St Augustine grass is susceptible to cold damage. For this reason, recovery is going to be very important during this growing season . It is even more critical that we reduce as much stress as possible to encourage recovery. The first step, fertilization, is to provide nutrients the grass needs. According to Dr. Ron Strahan of the LSU AgCenter, St Augustine lawns should be fertilized three times annually : mid – April, mid – June, and mid – late August. If you choose to apply a water soluble fertilizer such as 13 – 13 – 13 , the rate is 7- 8 lbs per 1000 square feet for each of the three recommended applications. Another option is a slow release fertilizer such as Scotts turf builder, or any other turf fertilizer that can be purchased at garden centers or at feed and seed stores. Follow the recommended rates on the bag or package. Finally, I have seen a major improvement of many St. Augustine lawns by simply following the recommended mowing height. St Augustine lawns should be mowed at 3 – 3 ½ inches, especially in shaded or areas or when we have very hot and dry conditions. This higher mowing height reduces stress and makes for a more healthy roots system This, in turn, means a more healthy vigorous lawn that grows thicker shading out weeds, resulting in deeper roots, which also increases drought tolerance.
Happy Gardening!!!
Gerald P. Roberts
On woody plants such as citrus, figs and many of our woody tropical plants, damage that was done by this winter’s freezing temperatures has become more evident. By now, you can look at plants and visually determine what parts of these plants can be pruned based on new growth. Brown areas can be pruned/remove up to healthy green growth.
Several callers have asked about reddish discoloration on amaryllis leaves. The reddish discoloration is cause by a fungus disease called red blotch which is common on amaryllis. According to Dan Gill, the most appropriate practice is to remove affected leaves if the infection is severe.
Finally, numerous St Augustine lawns suffered some cold damage from this past winter. Most people don’t realize that St Augustine grass is susceptible to cold damage. For this reason, recovery is going to be very important during this growing season . It is even more critical that we reduce as much stress as possible to encourage recovery. The first step, fertilization, is to provide nutrients the grass needs. According to Dr. Ron Strahan of the LSU AgCenter, St Augustine lawns should be fertilized three times annually : mid – April, mid – June, and mid – late August. If you choose to apply a water soluble fertilizer such as 13 – 13 – 13 , the rate is 7- 8 lbs per 1000 square feet for each of the three recommended applications. Another option is a slow release fertilizer such as Scotts turf builder, or any other turf fertilizer that can be purchased at garden centers or at feed and seed stores. Follow the recommended rates on the bag or package. Finally, I have seen a major improvement of many St. Augustine lawns by simply following the recommended mowing height. St Augustine lawns should be mowed at 3 – 3 ½ inches, especially in shaded or areas or when we have very hot and dry conditions. This higher mowing height reduces stress and makes for a more healthy roots system This, in turn, means a more healthy vigorous lawn that grows thicker shading out weeds, resulting in deeper roots, which also increases drought tolerance.
Happy Gardening!!!
Gerald P. Roberts
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