Phytophthora and leprosis diseases can each substantially reduce the productivity of a citrus tree, but when they attack trees already weakened by HLB, the result can be fatal.
Ozgur Batuman, assistant professor at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), explained how co-infection impacts HLB-infected trees during a recent UF/IFAS webinar.
Phytophthora species are soil-borne fungal pathogens found worldwide that attack the root systems, trunks and fruit of citrus trees at any age.
Diseases caused by Phytophthora species include brown rot, foot rot, crown rot and root rot. Brown rot can directly reduce yields of early-maturing varieties and can delay harvest of fresh market fruit or risk packinghouse rejection of the load because it can spread post-harvest. Foot root and crown rot can kill trees but are uncommon when the correct rootstock is chosen. Root rot can reduce tree vigor and fruit production.
According to Batuman, all of these diseases have been manageable in the past. However, management is complicated by HLB.
As the cycles of root production and disease become disrupted and fluctuate widely due to phytophthora and HLB infection, proper timing of fungicide applications become more complicated.
“In this case, improving fungicide timing, number and applications of rates are needed to achieve better control,” Batuman says.
While citrus leprosis is not currently present in Florida, it is considered one of the …..
Learn more about Citrus Diseases to Pay Attention to on the Citrus Industry website.