Farm Focus: Citrus Update #2


As we mentioned in January, one of this year's big projects was planting mandarins, those sweet little cousins of the orange that are super sweet and packed with flavor. We have planted a few varieties of mandarins including Kishu, Owari and the crowd favorite: the clementine!


Clementines are especially beloved for their sweetness, easy to peel skin and seedlessness. Seedless fruit are fascinating. Fruit is meant to serve as a vessel for seeds to grow new plants so the idea of a fruit without a seed is counterintuitive. Breeders have been able to select fruit that has a genetic predisposition to have little to no seeds. The amazing part is that these genes can get turned off and a previously seedless tree will start producing fruit with seeds... all it takes is being exposed to pollen from other citrus trees! For this reason all of the clementines are being planted with the other big block of clementines planted a few years ago, far away from the rest of our citrus. Unfortunately, when we planted this original block it included some non-clementine mandarins that could potentially trigger them to start having seeds. Luckily, there is a very cool fix! Next spring, with the help of Candelario, our grafting expert,  we will remove the fruit stock from these trees and replace it with clementine fruit stock from our existing trees. This means that instead of losing all of that good root growth we can keep most of the tree alive but also make sure we can maintain seedlessness in our clementine crop.

Citrus will fill in our late winter/early spring harvest gap so we can be harvesting 365 days a year and they tolerate drought conditions fairly well we will still face other challenges. One of the most ominous threats to citrus here in California is Huanglongbing (HLB) or Citrus Greening Disease, a devastating disease caused by bacteria Candidatus Liberibacter asiaticus and spread by an invasive bug called the Asian Citrus Psyllid (ACP). The ACP carries the bacteria in its mouth and when it or its larva bite into a tree it becomes infected. The disease can take many years to show symptoms but for infected trees there is no cure. Leaves shrivel up, fruit becomes small and bitter and death is certain. Meanwhile any ACP that feed on an infected tree will carry the bacteria on to their next meal.  HLB and the Asian Citrus Psyllid originated in Asia but were introduced to Florida in the 90s and has seriously threatened the citrus industry there, killing millions of trees. And now it is in California. So far the HLB disease has only been found in Riverside County but the Psyllid has been found as far north as SLO county. The state is monitoring it very carefully and periodically moves quarantine lines around to limit the spread of the disease and its vector.

It is certainly something we will be keeping an eye on but we think all the hard work is well worth the delicious winter California citrus!