TechNotes Nov. 13 - Fertilization, Pink Hibiscus Mealy Bug, Soil Temps

Late Season Fertilization Soon Approaching

In the northern United States, mid- to late-November is an excellent time for late season fertilization of cool season turfgrasses. At this time turfgrass plants have slowed or stopped top growth but root growth and photosynthesis continue Nitrogen is the most critical element in late season fertilization. Nitrogen will extend the greening time later into the fall, promote root growth, contribute to carbohydrate accumulation, and promote early spring greenup. The rate of nitrogen applied during the fall depends on the source but the normal recommended rate is between 1 and 1.5 pounds actual nitrogen per 1000 square feet.  

The type of nitrogen source for late season fertilization varies considerably. Generally, the further into autumn you go, the more likely a quick release nitrogen sources may be used. In areas where moisture is adequate in the autumn, a slow release nitrogen source like IBDU may be used since it is dependent on moisture for release. Temperature dependent nitrogen sources like organics, methylene-ureas, sulfur-coated and poly-coated ureas work well but are more efficient in releasing nitrogen when soil temperatures are above 50 degrees Fahrenheit. Most fertilizers used in late season applications have a blend of slow and quick release nitrogen sources.

Winterizing fertilizers are often used in late season fertilization programs. A winterizing fertilizer has a significant proportion of potassium.  Potassium has been reported to enhance winter tolerance of bermudagrass. However on cool season grasses no such effects have been found. The important element is nitrogen in late season fertilization of cool season turfgrasses. Late season applications should be timed so that release occurs when top growth has ceased but the turf is still green.

Parasites Control Pink Hibiscus Mealybug

For four years parasitic biological controls have been released in 34 Florida counties to control pink hibiscus mealybug (PHM). Florida Department of Agriculture and Consumer Services is calling the program a success. More than two million gnat-sized wasps have been released in every infested county. At study sites in Broward and Miami-Dade counties, adult PHM female populations dropped 97 percent. PHM feeds on sap and releases toxic substances that cause plant injury and sometimes death. PHM infestations are spread by wind, on infected plant material and by ants or other small insects. 
 
Provided by: Green Beam

Soil Temperature Map