Blueberry season will begin to wrap up next month, as late rabbiteye cultivars will be at mature fruiting stage. This is generally the time of year when we receive seemly, daily afternoon thunderstorms. These rains can compromise blueberry plants long term, if management measures are not in place.
Rabbiteye cultivars are more popular in the Panhandle than southern highbush. Our environment is more hospitable to rabitteye, plus they’re a favorite of backyard growers as they tend to be more drought tolerant and less susceptible to disease. The harvest season for rabbiteye blueberries extends from May to July, depending on the cultivar.
Phytophthora root rot is a potential problem this time of year, due to increased rain events and poor draining soils. This is caused by the fungus, Phytophthora cinnamomic. This can lead to plant death, if not managed. It’s a condition that is easier to detect than most diseases. A clear sign is if your plant is experiencing symptoms of fall color development with foliage of yellow, orange and red, such as with the hardwood trees. This is followed by leaf drop. A fungicide can be used to treat this condition, but cultural methods as transplanting in well drained soils and using at least 3” of pine bark as mulch, will greatly reduce the risk of susceptibility. Remember, blueberries, like azaleas and camellias are acidic soil loving plants too. Soil pH range of 4.0-5.5 is necessary for overall plant health and high fruit yields. Pine bark mulch will help assist in maintaining an acidic pH.
Botrytis flower blight or gray mold, caused by Botryospheria spp., can be an issue in late spring/early summer, due to lingering moisture. Avoid any overhead watering during the budding and flowering stage in the future. Stem blight can occur this time of year. Symptoms are of dying branches, which can be simply be removed with sharp shears. There is no chemical control for stem blight. The best defense against stem blight is good cultural practices that will in turn reduce plant stress.
With summer temperatures and rainfall, often follows an increase in insect populations. Most insecticides that are safe for ornamental landscape plants and fruit crops should be safe for blueberries, just be sure to check the label for application rates, directions and precautions. Also, pay close attention to the label for the HI or harvest interval. This is the number of hours or days that need to pass before you can safely harvest fruit once an application of insecticide is made. For more information on growing blueberries, please contact Gulf County Extension at 639-3200.
Supporting information for this article can be found in the UF/IFAS EDIS publication, “2017 Florida Blueberry Integrated Pest Management”, by Jeffrey G. Williamson, Phillip F. Harmon, Oscar E. Liburd & Peter Dittmar: http://edis.ifas.ufl.edu/pdffiles/HS/HS38000.pdf
& “Blueberry Gardener’s Guide”, by J. G. Williamson, P. M. Lyrene, and J. W. Olmstead: http://edis.ifas.ufl.edu/pdffiles/MG/MG35900.pdf
UF/IFAS Extension is an Equal Opportunity Institution.