San Joaquin County walnut trees received plenty of chilling hours this winter, and as a result this month trees were advancing faster than normal, sayss Joe Grant, University of California Cooperative Extension Farm Advisor for the county.
He attributes that development to some unseasonably warm weather in February.
“The way things look, we could see bud break on Serr before the end of March, which would be a week to 10 days earlier than normal. We have a lot of Vinas and Tulares that should start leafing out not long after the Serrs.”
That’s the good news. The bad news is that rainfall this winter has been only about half the norm, Grant says. Some growers began irrigating mid-winter when the deficit grew.
“We like to see orchards start the season with the soil profile full of water,” he says. “Many growers have irrigated several times this winter.” Soil moisture isn’t abundant, but it should be adequate. “Growers will have to rely more on groundwater this spring than they had hoped,” Grant says.
An upside to a dry spring could be less pressure from walnut blight, which likes wet conditions after trees leaf out.
Grant doubts that Botryosphaeria, another walnut disease encouraged by wet weather, will be the problem for some growers this year that it was in 2011. The disease, which kills tender green shoots and stems and causes abortion or poor nut quality, is a new concern. However, so far it has only affected a small amount of the county’s total walnut acreage.
Grant isn’t ruling out the possibility of a good size crop this year with normal weather.
“We’ve had two quite large crops in a row, and an older farm advisor would probably expect more moderate production this year. But, we were surprised by the relatively high production from last year’s crop following the big crop in 2010. It could be a strong crop this year — at least, we hope so.”