By Larry Duncan Citrus trees in Florida soils infested with diaprepes root weevil (Diaprepes abbreviatus) or sting nematode (Belonolaimus longicaudatus) frequently contend with devastating damage to their root systems. This is made even worse by root loss due to huanglongbing (HLB) disease. Where soil conditions are conducive to the insect or nematode, it is very difficult to prevent major economic …
Lessons on Yield and Root Health From Modified Nutrition
By Davie Kadyampakeni, Evan Johnson, Kelly Morgan and Ali Atta Citrus production in Florida has been decreasing over the last 15 years due to several factors, with huanglongbing (HLB) a major driver. This disease has severe effects on citrus growth and production, including stunted vegetative growth, misshapen small fruits and poor color development, root mortality, stunted branches, excessive fruit drop, …
Field Trials for Cultivar Evaluation; Soil and Root Health
University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) citrus researchers are collaborating on ground-breaking research projects to fight against HLB. They are working with researchers at the University of California-Riverside (UC-Riverside), Texas A&M and Washington State University on a project to field-test new citrus cultivars for tolerance or resistance to HLB. The research is funded by the U.S. …
Improving Root Health in the Era of HLB
Developing and maintaining a healthy root system is crucial for establishment and long-term productivity of citrus trees. The presence of HLB can greatly complicate citrus root-health management. The infection causes severe damage to fibrous roots that amplify the detrimental effects caused by other root pests and pathogens, such as phytophthora root rot. Due to HLB’s widespread presence throughout Florida, root-health …
HLB and Citrus Root Health
“We’re not going to have a silver bullet” for HLB, says Lorenzo Rossi, an assistant professor at the Indian River Research and Education Center. Instead, the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) root biologist says that researchers are trying to keep citrus producing profitably. Rossi described some of his research efforts that focus on root health …
Root Health Update
Evan Johnson, a University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) plant pathologist at the Citrus Research and Education Center, updates efforts to help citrus tree roots cope with HLB. He starts by noting that around 10 years ago he and former UF/IFAS researcher Jim Graham discovered “that HLB causes severe damage to the root system.” They hoped …
Micronutrients for Root Health and HLB
University of Florida researcher Jude Grosser, best known for his work on citrus breeding, has become a champion of micronutrients to improve root health and battle HLB. At a recent Highlands County OJ Break, he discussed the use of micronutrients, including why he got involved. “I guess just like any farmer, you don’t like watching your plants get sick and …
More SuperSour Rootstocks Under Study
“Superior New Rootstocks Can Make Citrus Profitable Again” is the headline of a recent U.S. Department of Agriculture Agricultural Research Service (USDA ARS) article. Kim Bowman, research geneticist at the USDA Horticultural Research Laboratory in Ft. Pierce, Florida, write the article. A slightly edited version follows: The rootstock and root system are what make trees strong enough to survive and …
PGRs Promote Tree Health
The use of plant growth regulators (PGRs) has been a popular method to treat HLB-infected citrus trees. The materials have continued to be applied in conjunction with trunk injection of oxytetracycline (OTC) to improve tree health. Tripti Vashisth, an associate professor of horticultural sciences with the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), has been studying PGRs …
The Relationship Between Roots and OTC Treatments
Back in the early days of the HLB fight, it was observed that what is going on underground in citrus tree root systems is just as important as what is happening aboveground. In 2013, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) and U.S. Department of Agriculture-Agricultural Research Service researchers published that 27% to 40% root loss due …
Growing Citrus With Soil Health in Mind
Herb Young enjoyed a 40-year career in the agricultural chemical industry, starting as a technical service representative and eventually becoming a product manager. During those years, he worked on various specialty crops across the country. About 25 years of his career was spent in field research roles. So, experimentation with crops and growing practices comes naturally to Young. He has …
Breeder Advice on Nutrition, Scions and Rootstocks
Citrus breeder Jude Grosser recently shared tips on tree nutrition and discussed some scion/rootstock combinations that should work well for trees producing juice oranges. NUTRITIONGrosser became very interested in citrus nutrition several years ago in an effort to keep his newly bred trees healthy in the face of HLB. The University of Florida Institute of Food and Agricultural Sciences professor …
Hairy Approach May Get to the Root of HLB
Developing disease-resistant, high-quality improved crop varieties may seem like a “hairy” task, but Texas A&M AgriLife Research scientists may have gotten to the root of the issue. A new biological technology that develops and multiplies disease-resistant citrus plants is under development by an AgriLife Research team led by Kranthi Mandadi. Mandadi is an associate professor at the Texas A&M AgriLife Research …
USDA Citrus Breeding Program Focused on Rootstock and Variety Solutions
The U.S. Department of Agriculture’s (USDA) U.S. Horticultural Research Laboratory in Fort Pierce, Florida, has been home to a citrus rootstock and variety breeding program for many years. Kim Bowman, a research geneticist, has been with the program for more than 30 years. More recently, Matthew Mattia, a geneticist, joined the breeding team. They provide an update on the program …
Using Cover Crops to Improve Soil Health
By Sarah Strauss, Emma Dawson and Elena Karlsen-Ayala The term “soil health” has become increasingly popular in the last several years. While there are many definitions of soil health, one of the more commonly cited ones is from the U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS). It defines soil health as “…the continued capacity of a soil …
Citrus Root Weevil Intercepted
U.S. Customs and Border Protection (CBP) agriculture specialists intercepted a species of citrus root weevil for the first time in Wilmington, Delaware, on May 22. They found the Cleistolophus viridimargo (Champion, 1911) weevil, a significant actionable pest, while inspecting a shipment of pineapples from Honduras. CBP said citrus root weevils pose a serious threat to the $3.4 billion U.S. citrus …
Valencia on US-942 Rootstock Is Favored Florida Tree
For at least the last four years, the Valencia SPB-1-14-19 orange has been the most-produced citrus variety in Florida, and US-942 has been the favored rootstock. So, it makes sense that the Valencia SPB-1-14-19 on US-942 rootstock has been the most-produced tree combination for four years running. That information was provided at April’s Florida Citrus Growers’ Institute in Avon Park …
Cytokinin Studied for Citrus Health Benefits
Tripti Vashisth, University of Florida Institute of Food and Agricultural Sciences associate professor, has been leading the research on how plant growth regulators (PGRs) can improve the health of HLB-infected trees. She’s conducted extensive research on the use of gibberellic acid. But she has recently begun to study another hormone, cytokinin. She gave an update on this work during the …
Citrus Root Structures: Lessons From Below
By Ute Albrecht There have been numerous reports of malformed roots in field-grown citrus trees recently. The rootstock propagation method is often suspected as the culprit. Before drawing quick conclusions, it is important to recognize that there are many different factors that can influence the root structure of a citrus tree aside from the propagation method. These include the genetic …
Progress in Developing Improved Citrus Rootstocks to Mitigate HLB
By Jude Grosser, Manjul Dutt and Fred Gmitter Exploiting citrus genetic diversity is the key to defeating HLB. Plant species have survived for millennia with evolving, hostile pathogens. This is possible through natural selection within genetically diverse populations. Tolerant or resistant individuals survive and intermate, get through the bottleneck, and the species evolves. Current citriculture is based on extremely limited …