Being Proactive to Mitigate Plant Disease: Treatment after Hurricane
Below is Part 2 of the two-part series, shared by NCPN-Citrus, exploring ideas for preparing for hurricanes that may damage high-value crops. Part 1 was published in the November 2022 issue of Network News. One of the basic tenets of preventing disease due to pathogens is proactively planting material that has been virus-tested. And one of the strategies for minimizing the devastation of hurricanes and other natural disasters is to proactively prepare to protect people, infrastructure, and—yes—even landscape and agricultural crops. According to University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), in their article Treatment After Hurricane, "Tree defoliation also poses the risk of Asian citrus psyllids being attracted to any new flush that the trees will produce." More on that below.
Part 2 of 2: Treatment after Hurricane Mongi Zekri, Robert E. Rouse, and Jonathan H. Crane University of Florida Institute of Food and Agricultural Sciences (UF/IFAS faculty recommend actions citrus growers can take to prevent further damage to root systems and future fruit drop following Hurricane Ian.
DEAL WITH PHYTOPHTHORA
If standing water has occurred in groves with phytophthora problems, growers should evaluate for root damage and treat accordingly. Floodwaters resulting from heavy rains can severely impact roots already diminished because of HLB disease. Phytophthora is a pathogen that attacks citrus tree roots which are already weakened by HLB. Wet conditions, especially flooded groves, increase the possibility of phytophthora infection in groves with historical problems.
USE GIBBERELLIC ACID
Hurricane Ian caused fruit to drop from trees but also weakened fruit left on trees. Tripti Vashisth, associate professor of horticulture, recommends applying gibberellic acid (GA) in the next few weeks and prior to Oct. 30 to support the tree’s ability to hold its fruit. “Extensive leaf loss is going to stress already stressed trees,” Vashisth said. “It is quite likely that extensive leaf loss with good soil moisture will induce new growth. GA application at this time can help with rehabilitating the trees and improve the leaf growth.” Some growers are already using GA in a series of applications to improve fruit production and should continue to do so. Growers not using GA in this way are encouraged to make at least one application to encourage leaf growth lost to the hurricane, which will support future fruit production. Read more on applying GA.
WATCH FOR PSYLLID FLAREUPS
Tree defoliation also poses the risk of Asian citrus psyllids being attracted to any new flush that the trees will produce. It would be wise to watch for pest flareups associated with intense flushing later in October in those areas where groves were heavily defoliated by Ian.