Citrus greening disease, also known as Huanglongbing (HLB), is one of the most severe plant diseases in the world. It can affect any variety of citrus trees. Once a tree is infected with the disease, there is no known cure. Although the disease is not harmful to humans, fruits from infected trees are not suitable for consumption because of their green color, misshapen appearance and bitter taste. The disease has devastated millions of citrus trees in the United States.
Greening was detected for the first time in the United States in Homestead, Fla., in August 2005. Florida growers watched as a tiny insect called the Asian Citrus Psyllid (ACP) spread HLB into commercial citrus groves throughout the state. HLB, or citrus greening, is now found in all of Florida’s 32 commercial citrus producing counties.
The bacterial disease is spread by the Asian citrus psyllid and it attacks the vascular system of citrus trees often killing them within two years. Fruit on infected trees often falls to the ground before harvest, and fruit that remains on trees may become misshapen and sometimes only partially ripen. The ACP and HLB have also been found in other U.S. citrus producing states, including Texas and California.
Florida growersfirst mode of action was to scout their groves for the disease and remove all infected trees. However, the disease had spread so much that growers realized that they could not keep ahead of the disease and they would soon be out of business.
Growers decided to learn to live with the disease and prolong the viability of their trees. The current program in Florida is to spray, on a regional basis, for psyllids to keep their populations low and to spray the trees with extra foliar nutritional sprays several times a year. One of the effects of HLB on the citrus tree is that it reduces the amount of tree roots and the ability of the tree to take up nutrients from the soil. By feeding the tree nutrients via foliar sprays, the tree seems to respond and maintain production longer. These extra sprays have caused growers production costs to increase 40 percent in many cases.
Florida growers are currently experiencing a record amount of fruit drop this season. The USDA reported that the 2012-13 season fruit drop is projected to be the highest since the 1969-70 season. Experts believe much of the reason is due to the effects of HLB reducing the root systems, and the trees ability to hold all of its fruit. The USDA has reduced the crop estimate twice this season, 5% in December and another 3% in January. The original October 2012 Florida orange estimate was for 154 million boxes, but has now been reduced to 142 million boxes for the 2012-13 growing season.
These nutritional sprays seem to help the trees tolerate the disease and may help keep them productive longer. Vegalab produces several products that are fertilizers, bio-fertilizers, bio-stimulants, that are all natural and might possibly be part of a nutritional cocktail that growers could include in their spray programs to help citrus trees ward off the effects of the disease. Many bio-stimulants, such as Armour Boost, with natural silica may build strong, disease resistant plants. This may help citrus trees become more tolerant of the disease.
To help ward off a reduction of roots caused by Greening Disease, Vegalabs Kelp Boost, a biostimulant fertilizer that increases nutrient uptake and secondary root growth via phytohormones, may help improve the citrus trees root system.
Vegalab also produces many natural pesticides that might offer a safe alternative to help control the Asian Citrus Psyllid. In fact, many pesticides now used to control psyllids, have the possibility to have the insects build up resistance due to repetitive use. Adding another mode of action into the mix is often recommended to alternate with other products so that the pest does not have a chance to build up resistance.
Vegalabs is testing some of their products on Florida citrus to see if they might be a help in combating the effects of citrus greening disease.