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Almond Grower Newsletter – March 21, 2011

Fungicides

Calls from two of our beekeepers last week are the catalyst for this Newsletter. Both called me in the middle of a warm (70 degree) day from an almond orchard where they were looking at their bees and both reported ground rigs spraying Pristine during heavy bee flight.

In past years I hadn’t been concerned with fungicide sprays because you don’t see dead bees in front of hives as occurs with insecticide sprays. Work by Eric Mussen, and others, has shown deleterious effects on bee larvae from fungicides, esp. Pristine and Rovral; more recent studies have shown that some fungicides, esp. Pristine, interact with chemicals that beekeepers put in their hives for varroa mite control to greatly increase the hazard to bees. Both of the beekeepers that called me were aware of these studies.

Some fungicides, esp. in combination with some other chemicals, can result in a significant setback for bee colonies, one that doesn’t show up until well after the bees are removed from almond orchards.

With one exception, all the beekeepers we work with are from Southern California or from the northern tier of states, and we have had few complaints from them re fungicides, Much of Dr. Mussen’s beekeeper input is from Northern California beekeepers, almost all of whom are queen breeders. Queen breeders follow brood cycles closely and are convinced that fungicides, esp. Pristine, are harming their bees and queens.

The major fungicide-bee concern is when fungicides are applied when almond orchards have a lot of exposed pollen, and most growers use caution when applying fungicides at this time by confining sprays to late-afternoon or nighttime. The possibility of fungicides contaminating nectar hasn’t been studied closely but its likely that fungicide-laden nectar is harmful to bee brood. Almond flowers don’t secrete significant nectar until after the pollen is gone (after pollination is done) a difficult concept to grasp.

While almond pollen isn’t released until morning, nectar likely remains at the base of flowers all day and night (you can shake a branch of flowers and see the nectar on your hand). Its hard to say whether nighttime spraying of trees after almond pollen is gone will prevent fungicide contamination of nectar. The best way to minimize possible fungicide contamination of nectar is for growers to release their bees after there is no more pollen in the orchard, i.e., after the pollination job is done, but few growers do this since they see nectar-collecting bees working flowers and are understandably reluctant to let go of the bees. I tried to assure the two beekeepers mentioned herein that since there was no pollen in the orchard, there should be no problem. I didn’t consider nectar contamination so I don’t know if my assurances were valid.

One way to eliminate fungicide-bee problems is not to spray fungicides. I don’t recommend this because I have seen first-hand what brown rot can do to an orchard, but Paramount Farming, the largest grower in Kern County uses minimal or no fungicides on the vast majority of their acreage. Are they crazy, or do they really know what they’re doing? I opt for the latter since I know the people in their organization and know they don’t make any management decision without careful examination of all facets of an issue. Re bloom diseases, they work closely with the most knowledgeable almond-bloom disease person in the world, Jim Adeskaveg, UC, Riverside and closely monitor ranch test plots with him.

Paramount has concluded that most fungicide sprays are not cost-effective — that any increased yield does not cover the extra expense. There are exceptions, and orchards with a history of disease problems are treated with fungicides. There are varietal differences in susceptibility to fungi, with Nonpareil being somewhat tolerant and Butte somewhat susceptible.

I discussed fungicide sprays with Dr. Adaskaveg last week and he said the most important consideration is the disease history of the orchard (and the amount of inoculums present). Jim stressed that disease history and inoculum is much lower in Kern County than in wetter regions to the north, and he’d be very cautious about minimal spraying in areas that get more rain (this Newsletter is directed to Kern County growers and to some Westside growers). It will be interesting to see if Paramount implements its Kern fungicide policy to its new ranch in western Madera County.

Whether or not to apply fungicides is the most difficult management decision a Kern County almond grower makes. The CYA syndrome is in full force here, with Pest Control Advisors wary of recommending not spraying at the risk of permanent damage to their reputations (if I was a PCA, I’m sure I’d be making a lot of fungicide recommendations). And, its difficult to refrain from applying fungicides when you see your neighbor’s spray rigs going full-bore.

Most of Paramount spray rigs have been eerily silent in recent weeks and it is worth contemplating why. One must give full props to Paramount for their fortitude in going naked on most of their blocks as they are under the same kind of pressure as PCAs. We all have to answer to somebody, if only to our most severe critic — ourselves.

Unlike some large concerns that value secrecy, Paramount is generous in sharing information with others. Many of the current cultural practices used by almond growers had their genesis in UC test plots in Paramount orchards. Because Paramount has the resources to thoroughly evaluate any management practice one could do well by following Paramount’s practices in almond culture. An exception would be the low-ball prices they pay for almond bees (hey, nobody’s perfect!).

McDonalds-Burger King provides an analogy here. McDonalds spent lots of resources researching the optimum locations for their “stores”. Burger King played copycat and simply opened up stores next to or across the street from McDonalds. There’s no stigma to being a copycat if you’re copying the right person.

Paramount has done the heavy lifting on fungicide sprays. Other Kern growers can benefit from their work. If nothing else, consider leaving a no-spray check area in your orchard; probably too late for this year, but maybe next year. And for alternaria, a May spray can usually substitute for a bloom spray.

The current almond set looks very good from Modesto south. The Sacramento Valley had poorer bloom weather and their crop will be lower as a result. Its still too early to tell how many nuts will stick. We need warm, sunny days to minimize nutlet drop and our current weather is less than ideal.

Jacket rot can be a problem with prolonged wet weather, but any recent fungicide applications should give you good protection. (Note: if Paramount comes down with significant jacket rot on their unsprayed blocks, please destroy this Newsletter).

Calcium has been shown to have anti-fungal properties so consider adding calcium nitrate to any spring nutritional sprays. And, if shothole is a problem, a fall zinc spray will help reduce inoculum. A Quik-test for inoculum of any bloom disease would be nice, but it doesn’t look like such a test will happen soon.

Thanks
Thanks for the prompt payment of your bee bills as I know this is a major cultural cost. Along with you, I am hoping that March will do what its supposed to do: go out like a lamb and that April and May will follow suit.

Joe Traynor