Growers pay a nominal fee to register and agree to plant at least a 1 acre solid planting.
Participants then provide feedback to guide release and commercialization decisions. The program is designed to reduce the time needed to evaluate and release new varieties.
Putting rootstocks to the test
To determine whether candidates possess a strong disease package, Grosser says they put them through a series of screenings that weeds out all by the fittest.
The rootstocks must pass greenhouse trials where HLB-infected budwood is grafted onto them and the movement of the bacteria monitored.
In addition, technicians plant the rootstocks in calcareous soil that has a pH of 8 and then measure nutrient uptake. Rootstock candidates also are planted in soil infested with Diaprepes weevils.
After the insects feed on the roots, the plants are moved to soil infected with phytophthora and monitored for disease.
The weevil feeding sites on the roots provide entryways for the pathogen. Plants with vigorous root growth can withstand the one-two punch and remain viable.
Other screenings include exposing the rootstock to all three citrus tristeza strains found in Florida as well as irrigating them with high saline water.