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Huanglongbing explodes across southern California

Deadly citrus disease quickly claiming residential trees across Los Angeles Basin

Can California conquer the deadly Huanglongbing (HLB) disease in citrus before it consumes the industry here as it has done elsewhere around the world?

Judging from last year’s explosion of HLB finds in neighborhoods across southern California, it doesn’t look good. Still, one bright spot remains: the disease has not been reported in commercial groves. Yet. I’m told the industry is currently planning for that announcement.

California’s industry-funded state program – the program designed by name to help beat back bugs and diseases that can wreak havoc on an iconic crop that pumps billions of dollars into the state’s economy each year – recently reported a massive uptick in positive finds throughout the Los Angeles Basin.

Last year 699 residential citrus trees were confirmed with the disease based on government-approved testing protocols, according to information from the Citrus Pest and Disease Prevention Program. Add to that the 269 trees discovered in 2017, the original tree from the 2012 Hacienda Heights discovery that released the proverbial genie from the bottle, and it doesn’t bode well for residents with citrus trees. The implications to commercial citrus farming in California are self-evident.

As of February 8, 1,079 citrus trees in three California counties tested positive for HLB and were removed by state officials – and that seems to be California’s best management strategy to at least slowing the disease spread. Yet it’s not the trees we must worry about, but the psyllids infected with the toxic bacterium they then inject into the trees when they feed that are quietly spreading the disease around.

Granted, there are huge differences in how these trees are cared for. Residents barely water their trees while farmers baby them by comparison. Commercial trees are treated with approved insecticides as necessary, fertilized when needed, and irrigated to maximize production and fruit quality.

Our urban landscapes are safe-havens for all sorts of invasive pests that found their way to the United States in luggage, postal packages, vehicles or natural migration. It’s not just the Asian citrus psyllid (ACP), the tiny bug responsible for transmitting a disease into citrus trees for which we currently have no cure. Researchers are also studying pests damaging to grapes, avocados and wildland vegetation across the southland.

In the case of the ACP, its movement throughout California can be directly linked to mankind’s inadvertent and in some cases, illegal movement of citrus plants and fruit around the state. A quick look at state maps showing where psyllids have been found reveal these bugs on most of our major transportation routes from San Diego to as far north as San Francisco and the Sacramento area.

It’s our fault these bugs are where they are. That a single psyllid was recently discovered in the Marina community of San Francisco pretty much proves humans are doing an effective job of moving the bug around and helping it establish.

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