Even though LSU AgCenter horticulturist recommends several species of plants that will perform under our stressful summer and fall growing conditions, I’d like to focus on a group that performs great and continues to perform well in AgCenter plant trials. That is the Profusion series of zinnias, with hybrids representing a cross between the old cut flower type zinnias and the Mexican narrow leaf zinnias, producing flowers and foliage that are smaller than the old cut flower type but larger than the narrow leaf zinnias. They are available in five colors: Profusion white, orange, cherry, with Profusion fire and apricot having the most colorful flowers in the series and are among the best performers. These zinnias are popular among both home gardeners and landscape professionals because of overall performance including attracting butterflies, resistance to pest, and once again heat and drought tolerance. They perform very well with limited irrigation and thriving under hot dry conditions. Planting dates usually begin in mid – late April or May and may extend into the summer months. A late summer planting will ensure a strong crop of flowers into the fall primarily in September and October blooming until the first killing frost. Profusion zinnias benefit from deadheading – removing the old flowers which encourages the production of more flower buds leading to more continuous blooming.
When chinch bugs affect lawns, specifically St Augustine, grass becomes pronounced when weather conditions become hot and dry especially during the summer months. I’ve looked at several St Augustine lawns where the home owner was concerned about areas of their lawn where the grass was turning straw colored and dying in an increasingly expanding irregular circle. Usually at this time of the year, I know because of information from LSU AgCenter horticulturists and past experience, that chinch bug is most likely the issue. If you suspect a chinch bug problem, there is a test that you can perform in the lawn to confirm. Take about a gallon of water mix in 2 – 3 ounces of lemon scented liquid dishwashing detergent and pour in the transition area on the outer perimeter of the circle where the brown and straw colored grass meets the green grass. Wait a few minutes and if chinch bugs are present you will see them crawling around on the stolons and leaf blades of the grass. The most likely areas for chinch bugs is a lawn in sunny areas between the sidewalk and street or along driveways. As soon as I notice lawns dying close to these areas I suspect chinch bugs since they like areas where the temperatures are the highest and these are the areas that absorb the most heat. There are several insecticide labeled for chinch bug control in lawns including bifenthrin, acephate, permethrin, malathion and cyfluthrin. The longer chinch bugs infestations are allowed to continue in a lawn the more likely it is that they will kill grass. I’ve seen several situations where the damage was so severe that the homeowner had to sod the area to replace dead St Augustine grass.
I’m getting numerous calls from homeowners reporting serious defoliation of crape myrtles with the leaves being yellow to reddish in color. This is the result of serious infection from a foliage disease called cercospora leaf spot , which is a fungus disease that attacks crape myrtles especially during high moisture conditions like we had in mid-spring and very early summer.
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