Scouting Tips For HLB
October 1, 2007 “If you start scouting now, you will be so much farther ahead.” That is the advice Timothy Gast, citrus horticulturist for Southern Gardens, gave a packed hall of growers during the recent Citrus Expo in Ft. Myers. Greening or HLB was the most discussed topic during the event, as the disease’s very real threat to Florida’s citrus industry continues to sink in.
According to Gast and other speakers during the event, scouting is the very foundation of living with HLB as effectively as possible, along with a good program for controlling the vector, the Asian citrus psylla. Southern Gardens’ 16,500 acres of groves are centered in and around Hendry County. HLB was first discovered in the company’s southern grove on Oct. 11, 2005. Since that first HLB find, Gast reports more than 100,000 trees have been removed from the farm’s groves.
Start Now
As painful as removing thousands of trees is, Gast says ignoring the problem will only make the situation worse in the future. After the October 2005 discovery, Southern Gardens kicked their inspection process in gear with general or “delimiting” surveys. Scouts utilized mules during this general survey and covered up to 30 acres per day. The delimiting survey took a little over a year to complete and consisted of two complete scouting cycles. The survey established the presence of HLB over the entire farming operation.
Gast says, if your scouting resources are limited, start by inspecting grove boundaries, along canals and roads, and along edges of grove boundaries. Also, scout young tree blocks first and take a good look at trees in poor soil areas and hurricane damaged trees because stressed trees tend to show symptoms earlier.
Detailed Inspection
After HLB prevalence was established with the delimiting survey, Southern Gardens turned to detailed inspections to further identify and remove infected trees. Scouts walk the groves and can cover about 6 to 8 acres per day while conducting this more in-depth inspection. Scouts work in pairs, walking both sides of the trees. Suspected HLB trees are marked by the scouts with a small flag on the symptomatic branch. The tree is also flagged on the bed top side to be easily spotted. The end of rows where suspect trees are found are also flagged.
Final confirmation of suspect trees is performed by well-trained senior scouts. The senior scouts look for the tell-tell blotchy mottle of leaves and green island zinc deficiency. Other symptoms include lopsided fruit and aborted seeds. Gast says the fruit symptoms are very reliable diagnostic tools, so all scouts carry fruit knives during inspections. When HLB-positive trees are identified, the locations are recorded with GPS devices and the trunks are painted with orange or pink florescent paint, so removal crews can easily spot trees to be taken out.
Higher View
According to Gast, many symptomatic leaves are high up in the tree and difficult for scouts to see from the ground. By early 2008, Southern Gardens plans to transition to scouting all fruit-bearing trees using raised platforms. The platforms travel at 2.5 miles per hour, with scouts up high on either side of the trees. Two scouts on the lower platform will perform logistics tasks of flagging trees.
Gast closed his comments by stressing that the only way to have any chance of managing HLB is to continually monitor for the disease and remove infected trees. That means scouting groves four times per year and spending the necessary resources to stay on top of the problem. Southern Gardens also is starting a program to monitor for psylla populations.
HLB/Greening Symptoms
• Blotchy mottle
• Green islands, which looks similar to severe zinc deficiency
• Fruit Symptoms — Lopsided fruit and aborted seeds
• Yellow shoots
• Yellow-veined leaves
• Vein corking on leaves
• Sectoring of chlorosis in the tree
• Severe fruit or leaf drop
• General dieback or decline
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