Growing citrus in Florida is challenging whether you are a commercial producer or a hobbyist gardener. Perhaps the biggest challenge to viable citrus production is HLB, short for huanglongbing, the endemic disease that has depleted about 75% of commercial citrus acreage in Florida over the past 17 years. The disease, also calling citrus greening, causes a wide array of symptoms from misshapen and poor-quality fruit, to fruit drop, to root and shoot dieback, to over all tree decline and death. The bacterial disease is caused by Candidatus Liberibacter asiaticus and is vectored, or spread, by a small flying insect called a psyllid, or the Asian citrus psyllid to be exact. The insect is well established in the state of Florida and it spreads the disease while feeding on tree leaves. There is no cure for HLB and researchers at the University of Florida and around the world are working towards solutions, including breeding new cultivars that will be resistant to the disease.
One of the best ways to combat this disease then, is controlling the psyllid. How does one keep little flying insects smaller than a millimeter from chewing on their citrus trees? An obvious answer to this could be insecticides. While spraying chemicals to control pests certainly has its place in agriculture and can be highly effective, this approach certainly has its limitations. In comes in individual protective covers, or IPCs. The simplest explanation of an IPC could be a fine mesh bag placed over a tree to block pests from getting to the tree. It is sort of like moving to a screened in porch to avoid getting bit by mosquitos or sleeping under a mosquito net in areas where malaria and mosquitos are of high concern. Mesh netting or screening is not a brand-new concept to agriculture. It has been used to keep birds, insects, and other pests away from crops for quite some time. But Florida citrus began adopting this practice as a means of psyllid exclusion and several models are available for commercial growers and hobbyist growers alike.
The covers are made of monofilament high-density polyethylene (HDPE) or polyvinyl and come in different overall sizes. They can be supported by homemade PVC stakes or other types of tree stakes and securely closed at the base with zip ties or other fasteners. The covers can remain on the tree for the first years (usually two) of its life. The idea is that if the tree can start off its life healthy and disease free, it will have a better chance of becoming a viable and productive mature tree once it is re-exposed to the unprotected environment. IPCs do not come without their drawbacks. Because they create a microclimate around the tree, they can tend to lend to other pest and disease pressures. However, as HLB is the biggest production threat to citrus, growers are often willing to deal more with other pests if it means they battle less with the greater threat of the Asian Citrus Psyllid and HLB cycle. IPCs can be viewed as rather unsightly, particularly in the home landscape, but this practice can prove a valuable tool in the toolbox for those that want to grow healthy and productive citrus. Homeowners can purchase IPCs at some registered citrus nurseries and online.
For further information, see:
- HS1425/HS1425: Individual Protective Covers (IPCs) for Young Tree Protection from the HLB Vector, the Asian Citrus Psyllid (ufl.edu)
- PP326/PP326: Frequently Asked Questions About Huanglongbing (HLB;citrus greening) for Homeowners (ufl.edu)