I have written articles in the past describing the problems of CG (Citrus
Greening)and ACP (Asian Citrus Psyllid) on citrus here in the Lowcountry. Everybody has heard and read about the problems and quarantines. New research has shown there is possibly some help in the future.
Researchers at the University of Florida Indian River Research and Ed Center are investigating a fungus that someday could be used in the fight against Psyllids.The vector that spreads Citrus Greening disease. The product is a microbial insecticide called PFR-97. The active ingredient is a naturally occurring fungus, which spreads among the pests after application. The product has been shown to be fairly benign to beneficial insects. It has also been shown to kill a wide variety of other citrus pests beside the psyllid. There are plans for larger field studies.
Then, there is the hope that planting and growing Guava with citrus will help repel the psyllid. In 2006, South Vietnamese farmers reported that planting guava trees among citrus trees reduced psyllid infestations and kept greening out of their groves. In 2007 horticulturalists and some growers went to Vietnam to evaluate the situation. While there, they observed that the guava effect appeared to be true. Scientists surmised that there must be something in the guava leaves because the psyllids were kept out all year round and fruit is on the tree for only part of the season. The scientists then discovered that damaged guava leaves produced dimethyl disulfide, which is very toxic to most insect species. Hence, it appears that when guava leaves are wounded by insect attack, they produce the dimethyl disulfide. This is one possible explanation for the repulsive effect of the guava on the psyllid. There is hope that some kind of method can be developed that uses these findings and keep the psyllids out of citrus groves and slow the spread of Greening.
This then gives us a good excuse to grow some more unusual plants. Like we needed a good excuse right? Why not plant a guava tree? The guava thrives in both humid and dry climates. It basically can be treated like citrus. Some frost protection maybe needed. Older trees, killed to the ground, have sent up new shoots which fruited 2 years later. The guava seems indiscriminate as to soil, doing equally well on heavy clay, light sand, and tolerating a pH range from 4.5 to 9.4. It is somewhat salt-resistant. Good drainage is recommended but guavas have been seen growing spontaneously on land with a high water table,too wet for most other fruit trees. Guava seeds remain viable for many months. They often germinate in 2 to 3 weeks but may take as long as 8 weeks. Guava trees grow rapidly and fruit in 2 to 4 years from seed.
Water requirements are right around 60 inches per year, (Charleston averages around 50). So, needless to say, planting a guava could be a good choice for another unusual tropical plant to keep your citrus company, it may also protect it from ACP and CG attack.
I have one Guava already growing and this past Fall, I planted a couple of other varieties. I will be ready, if/when the Asian Citrus Psyllid raises it's ugly head in MY yard!