California Pistachios: Lack Of Chill, Let’s See If The Oil Helps

    For Kern County at least, it looks like our chill accumulation for the year is over based on the weather outlook. Although it is becoming increasingly clear that we don’t know much about the topic, it appears that this year’s chilling is going to be on the deficient side for pistachio in most areas of the county.

    Fog this fall and winter was, again, mostly absent, and we had a lot of high temperatures through the winter in excess of 60 º F. We even had a few record highs for individual dates.

    It appears that we are going to have two years in a row of seriously deficient chill and what result this will have on the trees is anybody’s guess. A lot of dormant oil went out in late January and early February and is still going on at this writing. In fact, 470-weight oil was tough to get.

    A number of growers sprayed half a block and left the other half untreated. Thanks to the cooperation of an interested grower, we were able to establish a replicated trial with dormant oil, which included unsprayed controls, treating both the male (Peters) and female (Kerman) trees, or treating only the male trees. It should be interesting to compare results in this trial with other trials during bloom and later at harvest.

    I have received a number of calls asking why the Shafter CIMIS station was ‘reading’ much cooler than other CIMIS stations this winter. I contacted the person responsible for the station and discovered that a temperature-recording sensor (we don’t use thermometers anymore) was defective in December and replaced.

    Temperatures recorded since this time should be accurate. In an often uncertain world, installing a temperature recording device of your own in your own orchard is a good idea; I just wish we knew more about what to do with this data once downloaded.

    From: Kern County Pistachio Notes Newsletter, Feburary



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