Florida Citrus Tree Rehab in Full Swing After the Storm
When Hurricane Irma swept across the state in September, it left a path of destruction that won’t soon be forgotten, especially by the state’s citrus growers. But they are a resilient lot and those with the financial ability to weather another bad season are back out in groves trying to rebuild the health of damaged and stressed trees.
Southern Gardens Citrus was among the farms that took a hard hit from the storm. According to Jim Snively, Vice President of grove operations for the company, his production team was back in groves as soon as possible to clean up and begin rehab. He adds it was not nearly as bad a storm as Hurricane Wilma in terms of tree loss.
“We had significant fruit loss in the groves, which right now we estimate at 40% to 50%,” he says. “We have a little heavier loss on the early-mids than the Valencias; but both were significant.”
Snively says there was tree damage in terms of twigs and leaves blown off, but actual tree loss was minimal. The Southern Gardens’ groves saw winds of about 80 mph with gusts up to 110 mph with Irma.
“We had water up on trees for about 24 hours that took us a week and a half to get down to what we consider a manageable level,” Snively says. “Because we kept the water moving, we don’t expect to see any significant root damage.”
After the initial loss from fruit that was blown off, Snively has seen continued drop in the weeks following the storm. As time as goes by, it has lessened, but he expects drop with the early-mids to continue up until harvest.
Back in Action
Snively says the rehab process will surely be complicated by HLB. The disease leaves many unknowns moving forward, as this is the first major hurricane with HLB endemic in virtually all of the state’s citrus groves.
“The first thing was to get water off the trees,” Snively says. “One of the major concerns, particularly on our early-mids, was brown rot, so we immediately applied a copper and phosphite spray to try to minimize the impact of brown rot and Phytophthora. We also injected phosphite in the irrigation to help with root stress and to recover from whatever damage was there. That took us about two and a half to three weeks after the storm.”
After that period, Snively says finger flush started showing up in trees, so psyllid populations began to grow rapidly. Insecticides were added into applications to keep the pest in check.
“Because of the flush, the psyllid pressure was a little heavier than we would expect in the fall, but that is mainly because the flush was heavy after the storm,” Snively says. “We also put in pretty heavy foliar nutrition with the applications. It had potassium nitrate and minors like magnesium, manganese, iron, and zinc. We also added phosphite in the spray as well to help the root stress.
“We were already scheduled to do this spray, but we added a little more to it as far as nutrients go. Also with our fertilizer program, once we got the water down, we got back to our fall fertilizer applications. We are not backing off our rates. We feel it is more critical now than even before, because we have to build the trees back up more than before the storm.”
Calling for Researcher Support
UF/IFAS is a go-to source for production information and that was no different after Hurricane Irma.
Evan Johnson, a Research Assistant Scientist of plant pathology with UF/IFAS, specializes in citrus root health and says attention to root health is important after a flooding event. Setting flooding aside, growers are paying more attention than ever to root health because of HLB.
“The fall root flush has ended, so there is little that can be done currently to protect the roots if you have not already applied Ridomil (mefanoxam, Syngenta) or phosphites,” Johnson says. “The concern is that a large Phytophthora population may have developed on that flush. If you suspect a problem, you should monitor Phytophthora populations in the spring when soil temperatures rise. If economics allow it, a preventative phosphite application at the end of the spring flush would limit any Phytophthora development until its populations in the grove can be assessed. However, it is important to note that HLB reduces the effectiveness of chemical management of Phytophthora.”
Desperately Seeking a Better Season
Snively says most growers who felt the worst of the storm are unfortunately facing another financial loss this year.
“We have had three bad years in a row and this was the season that was looking good to make some money,” he says. “Then the storm comes and knocks that away. A lot of growers already had spent all they were going to on this crop before the storm. Those with heavy fruit losses probably don’t have funds to support growing next season’s crop.”
Snively says he is hopeful state and/or federal relief funds will be provided to growers hit hardest by the storm considering its impact and the ongoing decade-long battle with HLB.
“With this hurricane, we are coming off the worst times we have ever experienced and there is nothing in the bank account to help us through another year,” he says. “You take our situation here it Southern Gardens, we need some help, but if you go over to Immokalee, there are some growers there that are in a lot worse shape than we are.”
Planting Full-Steam Ahead
According to Snively, the storm will not halt Southern Gardens’ planting program.
“We have been on an aggressive re-set program since 2010, and we are not backing down,” he says. “We also have fallow land. As long as we can get funds, we will try to replant.
“We are looking more at ‘US-942’ rootstock and would like to use a little more of that,” he says. “We are still using ‘Swingle’ and ‘Carrizo’ and a little of ‘US-802’ and ‘X639.’
“We also are really interested in ‘Volkamer’ going forward. I️t is lemon-type rootstock that has been around forever, but it is very vigorous and seems to reproduce phloem at a higher rate and seems to tolerate HLB better.”
Snively says they will plant Valencia on the lemon roostock because Hamlins won’t get good Brix on it.
“As far as varieties go, we are planting some ‘Vernia,’ but we are still planting Valencia and Hamlin. We can definitely see Valencia holding up better than Hamlin, so when we are changing a block over, we look at changing it to Valencia.
Assessing Root Damage
After a hurricane or major rain event, citrus roots can be damaged by standing water. Understanding that damage is important in order to make good management decisions going forward.
According to Johnson, a quick and simple assessment would be to use a shovel under a couple trees to expose a small area of roots. A general assessment of overall root health can be determined by the “crunch factor,” which refers to the feel and sound of cutting through fibrous roots when inserting a shovel or soil probe into the ground in the wetted zone under the tree.
You also can look at the exposed roots for quality. White or very light tan/yellow roots are new growth. Existing roots are light brown and remain intact when handled. Damaged roots will be reddish to dark brown. They will have a mushy texture when handled and the root will often slough off leaving behind the fibrous core.
“With the current status of HLB and its effects on the root system, it is difficult to assess whether the damage is due to flooding from the hurricane or HLB,” Johnson says. “To specifically assess the damage from storm requires historic root density and Phytophthora data, then taking post-hurricane soil cores for the same analysis and comparing the two.”