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lemons in the greenhouse

Ep. 1: Rediscovering Traditional Farming Knowledge amongst the Florida Citrus Greening Disease.

Ep. 1: Devastation

Huanglongbing (HLB), or Citrus Greening Disease, entered Florida from China in 2005. HLB carries a deadly plant pathogen called Candidatus Liberibacter spp. which is vectored by a 3mm insect named the Asian Citrus Psyllid (ACP). Psyllids are insects with sucking mouthparts, and it is through this sucking that they transfer the bacteria to their citrus host. [1]

Candidatus Liberibacter spp.

Severely infected trees produce green, misshapen fruit that is bitter and inedible.

In a 2018 Ted talk [1] about the effect of Citrus Greening on the Florida Citrus industry, Agrocologist Stephen Futch describes the non disease-related problems farmers were facing in the Florida citrus industry: increases in land prices, water shortages, hurricanes, drought, and labour shortages; all of which have doubled production costs between the years 2000-2018. Ontop of this, new environmental extremes are forcing governments to declare states of emergency; as seen this year with a freezing emergency. Citrus Greening (or HLB) adds an additional blow…

In 2004 Huanglongbing (HLB) was found in Brazil (the worlds largest orange juice producer) and in 2005 HLB entered Florida and infected all their citrus varieties. HLB is declared the worst disease worldwide for citrus; infecting Texas, California, Mexico, China, and Brazil. In Florida, between 2002-2018, citrus production dropped from 850,000 acres - 400,000; a 48% decrease in 15 years. Grapefruit production dropped 82% from historic highs in 2018. [1]

HLB primarily attacks the tree roots, which decrease the surface area available for uptake of plant nutrients. As a result, the plant leaves show extreme levels of nutritional deficiency. There is currently no known “one” cure for HLB according to traditional paradigms. [1]

Unfortunately, many citrus growers relied on their annual Florida Citrus Production guides for advice [2] and were met with much the same “business as usual” Best Management Practices. Recommendations to deal with HLB in the 2020-2021 Florida Citrus Guide primarily include insecticide use: “The use of insecticides to control Asian Citrus Psyllid is a major component of HLB management strategies in Florida and elsewhere” and “Soil applied systemic insecticides have historically provided the longest-lasting control of psyllids with the least impact on beneficial insects”. However, they do recognize that excessive spraying “could result in the resurgence of [other] pests”. A large portion of these management guides discuss the risk of pesticide resistance in insect populations.

Other Best Management Practices put out by the Florida Citrus Production guides to deal with HLB include: decreasing water volume and increasing frequency of watering to the stunted HLB citrus roots, as well as disseminating smaller doses of nutrients to the soil, primarily in a form that is a “Controlled Release Fertiliser”.

Foliar nutrition sprays are also being used by the industry, which under such dramatic root loss conditions, seems necessary to keep the plants alive.

Long term solutions being proposed by the industry are to find trees that are resistant to the disease (whether GMO or not) and re-propagate citrus on new groves. [2]

No where in the 2020-2021 Florida Citrus Production Guide

do they mention the role of soil biology in plant resistance to disease.

$700M so far has been spent studying this problem. The National Academy of Science published a 180 page report on HLB and found no single solution. [1]

The Florida citrus industry has an annual economic impact of $6.7B [3], with $1B being lost to the economy every year due to HLB [1]. 60% of growers have left the industry within the last 5 years, and half of their land is being sold to developers. Farmers who are not selling their land are trying to diversify what they grow. [3]

Today (2022), the USDA says the citrus industry will produce the smallest amount of citrus in 80 years. [3]

90% of the US’s orange juice comes from Florida. Consumers in America have seen a 25% increase in the price of orange juice this year due to HLB. [3]

Typically, the lag time between innovation and adoption can sometimes be between 5-6 years. [1]

Do they have that much time?

All of this sounds pretty grim, but this devastating event has forced some citrus growers in Florida to innovate on their own and question the current “Best Management Practices” presented to them since the 1930s and 1970s by Universities, Industry and the Government. One such man is a Florida citrus grower, Brad Turner, with 40 years of citrus growing experience. In 2021, Brad won an Agricultural Environment Award from the Florida Department of Agriculture and Consumer Services for his work with Citrus Greening disease, cover crops, and soil biology remediation.

Article written by Odette Hobbis



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