Most of the questions involve whether or not anything can be done to address these problems, and my response is always that we need to hope for improved weather conditions. When conditions are favorable for pathogens to become active or once infection takes place, we are limited in what we can do. Applying fungicides in the middle of consistent rainfall is an uphill battle. Additionally it must be understood that leaves that are damaged by fungal infections will not be repaired with the addition of fungicides. Also once a plant suffers root rot, full recovery rarely occurs. Fungicides can slow down and protect undamaged tissue from further infection but these cannot guarantee prevention, especially when conditions are favorable for disease development.
Weed problems in lawns are at an all-time high, especially in lawns where drainage is less than ideal or in areas that received an abundance of rainfall. To control broadleaf weeds in lawns is normally as simple as applying a herbicide that controls broadleaf weeds. If you can recall some of my previous horticulture articles, I cautioned against applying broadleaf herbicides such as Weed B Gon or Weed Free Zone. Both contain a small percentage of 2,4-D. Both are effective, but when temperatures rise into the high 80’s or 90’s, lawn grass yellowing can rise to unacceptable levels. For broadleaf weed control at this time of the year and with temperatures on the rise, you can apply MSM Turf at the rate of ¼ teaspoon for every two gallons of water (or 1/8 teaspoon per gallon of water), evaluate and repeat in six weeks if needed.
There is a big problem now with dollar weed in lawns primarily because dollar weed favors high moisture and once again we have had our share of rainfall this spring. I need to warn Master Gardeners regarding an issue that has occurred with the application of Scotts Bonus S Southern Weed & Feed 4 on Centipede lawns. Based on Centipede lawns that I’ve gotten calls about and what Dr. Ron Strahan has seen, there have been serious injuries and death to Centipede lawns treated with this product, especially in early spring. For this reason, Scotts has pulled the product label for the Scotts Bonus S Southern Weed & Feed 4 with Metsulfuron on Centipede lawns. The older formulation of Scott’s Weed & Feed contained atrazine – not metsulfuron. Don’t apply the Scotts Bonus S Southern Weed & Feed 4 on Centipede lawns. There are no issues with St Augustine lawns or Bermuda Grass lawns, but there have been issues with Centipede lawns. If you or someone you know applied this product to a Centipede lawn and experienced injury or death, contact Scotts’ customer service hot line and report the problem.
Problems with crawfish holes and chimneys in lawns have surfaced again this spring. Because of the abundant rainfall, there seems to be more than usual. Many homeowners feel that dirt chimneys interfere with mowing and will dull the blade of lawn mowers. These homeowners are calling and asking for recommendations. There is no pesticide labeled for crawfish control in home lawns. That said, how do we get rid of them? Putting pesticides down holes/burrows can potentially contaminate ground water, plus it’s illegal. Pouring bleach down burrows/holes is often ineffective. According to Dr. Greg Lutz, Professor of Aquaculture with the LSU AgCenter, lye seems to work. Putting about a tablespoon full of lye usually does the job. As the lye migrates through the surrounding soil, it turns into harmless by products. BE FOREWARNED: lye is caustic, so wear hand and eye protection when applying.
I received a call from someone asking me why their agapanthus was not blooming or blooming very little. I contacted Dan Gill and Dan expressed the following opinion: If an agapanthus has bloomed very lightly for years, it is probably doing all it can under the conditions it is growing. It is likely just the way that agapanthus will bloom in that location. Flowering habits can but don’t normally change patterns following several years of flowering a certain way. Many people think that their agapanthus should bloom more or would like them to bloom more. Agapanthus plants will produce a certain number of flowers regardless of our wishes. All we can do is give them appropriate care, and enjoy the flowers they provide. White is a color sometimes seen in agapanthus, although blue types are more popular. Occasionally a white agapanthus will show up in a planting of blue ones. This likely occurred during potting up by the grower or indicates a spontaneous mutation, or the possibility that a seed falling to the soil has a plant genetically different from the parents (white, for instance, instead of blue). The dark bloom varieties, like Ellamae, tend to bloom later than the light blue types. That could be a reason why a clump may not be blooming now. Another possible reason is if they’re growing in too much shade,, or the variety or if they were divided when the clumps were small in size. I usually tell people not to give up until the end of June. This is the very beginning of the blooming season, and some varieties bloom later than others.
I am also getting many calls on small insects congregating in groups on smooth bark trees like crape myrtles. Many of the calls refer to webbing association with these insects. These are bark lice which are scavenger insects that are harmless to trees, so there is no reason to apply an insecticide.
Gerald P. Roberts Horticulturist/Master Gardener Program Coordinator LSU AgCenter 1010 Lafayette Street, Suite 325 Lafayette, LA 70501 GRoberts@agcenter.lsu.edu Office (337) 291-7090 Fax (337) 291-7099