Farm Focus: Protecting Our Citrus
As the citrus is starting to ripen in the orchard outside the offices we’ve been gearing up for the winter season which surprisingly means there is a LOT of paperwork. As a grower, packer, and transporter of citrus, we have to maintain “compliance agreements” for each part of our operation. The agreement lays out all of the specific precautions we need to take with citrus to keep our trees and yours protected. All because of a bacteria carried by a tiny insect from China that is threatening citrus crops across the state and the nation.
First a little bit about citrus…The first citrus thought to be the Pomelo, originated in Asia. These huge, thick-skinned fruit can have fruit up to TEN POUNDS and have the most punk-rock scientific name ever: Citrus maxima. Pomelos are joined by a few other ancestral species like mandarins and citrons. Their resulting hybrids, both wild and cultivated, make up the wide variety of fruit we know today including lemons, oranges, grapefruit, limes, and kumquats! Like most modern fruit trees, they are made of rootstock and fruiting stock grafted together for a strong, healthy and disease resistant tree. Unlike stone fruit, however, citrus are evergreen trees meaning they don’t lose their leaves in the winter which also happens to be the time of year they bare fruit.
Do you remember how there used to be advertisements for Florida orange juice on TV every time you turned it on in the 90s? Those happy farmers soaking up Florida sunshine in lush green orchards drinking big glasses of fresh orange juice were everywhere. That was before the arrival of the Asian Citrus Psyllid (ACP), a small insect that happens to sometimes carry a bacteria called Huanglongbing (HLB) or Citrus Greening Disease. The ACP first arrived in Florida in the late 90s and quickly spread across the state.
The ACP itself seems like a fairly unremarkable pest. They are about the size of a grain of rice and attach their mouths to tender leaves and stems to suck out nutrients from citrus trees. This results in two things: wilted/curled leaves and, more importantly, the risk of being infected with the bacteria for HLB. The bacteria enters the tree through an infected psyllid’s mouth and can remain undetectable in the tree for up to 2 years while it continues to infect any new psyllid that attaches itself to the tree. The disease causes leaves to shrivel and fruit to never ripen, hence the name Citrus Greening Disease.
Worst of all there is no cure and it is 100% fatal for an infected tree. Remember all of those Florida orange orchards? The ACP arrived in Florida in 1998 and 10 years later was found in every county across the state. Production took a major hit and millions of trees were lost. Of course, there are other influences here including hurricanes and economic factors, but the reality is stark. HLB is deadly serious, especially for a state whose economy depends on citrus like Florida and California.
And now both ACP and HLB are in California. Fortunately, so far, the disease has been contained to a few small spots in Southern California but Asian Citrus Psyllids have spread further, even up to Marin recently. Luckily, California has had the chance to learn a lot from Florida’s story and is working hard to protect crops, both commercial and homegrown.
In the meantime we are all geared up for a citrus season with our compliance agreements, making sure that we never pack any leaves or stems from the fruit we harvest and that we transport all of our citrus in covered vehicles. Plus all that paperwork from Contra Costa County, other farms, and the County offices where those other farms are to make sure we do our part to help contain this potentially disastrous disease.
What can you do? Glad you asked! There has been progress in prevention, including the use of parasitic wasps to manage ACP but there still aren’t many organic options to fight the bacteria. The best defense is to prevent the spread of the insect so both farmers and community members, need to be aware of this pest. Take some time to educate yourself and then examine citrus trees in your community, especially new, young growth that psyllids like best. Look for small, brown insects shaped like a grain of rice that stick their little butts up in the air while they feed. Their larvae excrete little white wax curls that are easy to spot. To learn more visit http://californiacitrusthreat.org/ or contact your County Agriculture Extension office.