Florida’s citrus growers have been battling something or other pretty much non-stop since the deep freezes of the late 1980’s. Today, one of the biggest challenges to Florida citrus is HLB, commonly referred to as citrus greening disease. Citrus greening disease is a highly destructive disease caused by the bacterium Candidatus Liberibacter asiaticus. The bacterium is spread from tree to tree by a flying insect called the Asian citrus psyllid. HLB suppresses root development, causing twig dieback, yield decline, and excessive fruit drop. Surviving fruit is small, green, and has a salty bitter taste. So rapidly did HLB spread throughout the state that homeowners were discouraged from growing citrus at home for fear that citrus psyllids could use them as waypoints to move more easily between farms.
However, with our view of HLB shifting from eradication to management in recent years, that view is changing, and two new citrus varieties are of particular interest, and while developed with the commercial grove in mind, both of them (and one especially) should make homeowners who want to grow citrus again smile. These varieties show tolerance to greening. It’s important to understand the difference between tolerance and resistance. Resistance means that a plant will actually resist getting a particular disease. Tolerance means that a plant will still get a particular disease but that it can remain productive.
Sugar Belle is a great variety that has proven itself in several commercial groves. While it does undergo a slight decline upon becoming infected with greening, it bounces back well. Sugar Belle reaches 12-15 ft at maturity. Harvest tends to come from mid-November through late December.
Plant breeding is the kind of science where you can never really predict the outcome. In University of Florida citrus breeding trials, one set of genetics in particular stood out for its great HLB tolerance. However, the yield wasn’t up to par for commercial growers. Instead of going to the grove, UF 13-51 is being heavily marketed as a dooryard variety, one designed for homeowners. While growers need a lot of fruit on a tree to make a profit, homeowners aren’t going to lose any money if a tree produces a little less than an amount of food they could never eat anyway. UF 13-51 reaches 12-14 ft at maturity and is harvested between late November and Early December.