Scientists say a bacteria found its way into clonal propagated pistachio tree rootstock from Duarte Nursery, one of the largest tree nurseries in California. Some young trees sold to farmers in California and in Arizona from 2011 to 2014 exhibit what has been called Bushy Top Syndrome affecting 20,000 acres and perhaps 2 million trees according to an estimate by Robert Klein, manager of the California Pistachio Research Board.
According to Klein the affected trees exhibit short stature, stunted growth in the limbs and roots with a bushy top somewhat like a witches broom.
The trees are weak and can be pulled up easily from the ground. Most cannot be successfully budded.
Farm advisors have recognized there is problem with the trees for some time although its cause was not known and no mention of Duarte as the source has been made public before.
Here is one description in the ag press.“Budders were having problems grafting buds onto rootstocks in several fields of young pistachio trees, which didn’t appear to be growing normally,” recalls Craig Kallsen, University of California Cooperative Extension Service farm advisor for Kern County. “As many as 60 percent of the buds didn’t take in some orchards.”
Late last year scientists announced the cause was likely from a new strain of bacterium – Rhodococcus fascians (Rf).
But Stanislaus County-based Duarte Nursery owner John Duarte, the only nursery implicated in the find, says he is not sure this is a disease. “If it is – it’s the strangest disease I’ve ever seen.”
Whatever is making this happen growers are pulling trees by the thousands wondering if getting rid of the trees will end their problem.
To make matters more complicated not all the Duarte delivered UCB1 clones exhibit severe symptoms says Klein, making it more difficult to replant,unsure if trees remaining will later show symptoms. If the problem is bacteria-based, there is also concern about spread of the disease either from the soil the trees are pulled from or farm implements.
“It’s a big can of worms” suggests Kings County pistachio grower Chuck Nichols who says he has 300 acres of trees that exhibit “significant busy top symptoms.”
Nichols says he was notified the trees had a problem by Duarte over a year ago but no compensation was agreed to. He says trees he bought from Duarte in 2007, 2008 and 2010 do not have symptoms.Of the 300 acres affected – Nichols says he has pulled out about 75 acres. With uncertainty about what to do about the rest of the acreage, Nichols sent out an ”open letter“ to pistachio growers earlier this month to see if others would join him to discuss “options” that may or may not include a lawsuit.
“I’ve heard back from 4” he says. Meanwhile, Nichols says he is aware of 6 lawsuits pending on the issue.Nichols says Duarte is not talking to him.
Duarte Nursery is a big player in the pistachio industry enjoying an estimated 70% market share for new trees by Nichols’ estimate.
Now owner John Duarte says because of the problem the nursery has suspended their clonal pistachio sales for 2015 “until we can figure out what is going on.”
Duarte has suspected the problem is a “genetic disorder” rather than a disease although he admits there are “still a lot of questions”.
If this is a disease “it’s new and unprecedented.” This bacterium never found in pistachios before, “is usually found in moist environments “ he adds, not in a dry climate like ours.
“Of course we are surprised but after all – this is farming, there is uncertainty.”
As to the issue of compensation Duarte insists he “working with growers” but the contracts that were signed included ”limited liability” protection for the company.
“There are a number of growers we have signed settlement agreements with and there are a handful who went out and got attorneys.”
The clonal produced trees developed by the University of California, have become the favorite of the industry in recent years.
Nichols says does not believe how the trees were propagated- as clones – makes them susceptible but has no idea how the bacteria infected this rootstock. ”It could have been spread by anything from water to bad luck.”
Klein says Duarte plantings can vary from 75% with symptoms to as low as 5%.He adds there is no reliable diagnostic test for growers to determine if a tree is affected putting farmers in a tough position.
Researchers like “ Elizabeth Fichtner, a University of California farm advisor in Tulare County, are looking at issues that include whether there is a cure for infected trees, whether it is safe to replant in the same holes from which infected trees were removed, and how likely bacteria is to be transmitted by farming tools that include pruning shears and grafting knives” says a recent ag journal.
One scientific report suggest symptoms make take a while to show up. “Within one to two years of t-budding, many trees exhibited unusual bark cracking around the bud union.”
Nichols says growers like himself are waiting to decide when to pull trees, whole groves or piecemeal, given it will take 2 to 3 years to make up for lost production.
As it is it takes 6 to7 year for healthy trees to put out a decent crop.
Because of surging overseas demand in recent years the pistachio industry in California has expanded rapidly planting thousands of new acres.
Now a series of setbacks are likely to ratchet back production.
Besides this problem there is the drought and a continuing lack of chill hours this winter adding up to lower production estimates despite all the new orchards coming on line.Confusion reins if the will be a ‘on or off’ year in this crop’s alternate bearing pattern.
Last year the state produced about 500 million tons.
Klein muses that this year “we could see anywhere from 300 to 700 million tons.”
Then there are other factors.
Last year for the first time China went to Iran where they had a good crop, to buy pistachios- looking for a better price.They did buy some U -grown pistachios but not as much.Then there is the strong dollar that makes our goods more expensive in other country’s currencies – hurting the entire US economy right now.
