Winter/Spring Conditions in California

This month we summarize winter/spring weather conditions in California with a special focus on stone fruit. Next month we focus on table grapes.

January Freezes

This year California experienced a devastating freeze which began on January 12 and continued for about 10 days with low temperatures ranging from about 17F (-8C) to 26F (-3C) each day. A wide variety of California’s fruit and vegetable crops were affected, including citrus, avocados, strawberries, artichokes, broccoli, celery, blueberries and cut flowers. The biggest financial loss, about $700 million, was with the state’s citrus industry, followed by avocado growers with an estimated loss of $108 million. Gov. Arnold Schwarzenegger has requested disaster relief for 24 of the state’s 59 counties.
 Stone fruit chilling and fruit set picture

The winter of 2006-2007 was the best for chilling accumulation in fruit growing areas of the San Joaquin Valley (SJV) since the 2002 season. The U.C. Fruit and Nut website estimates chilling accumulation at about 900-1100 CU, which is ample for all commercial cultivars. Even the Coachella Valley had good chilling accumulation, with 300-500 CU, depending on the growing area.

“Bloom was generally strong and compact, and the timing was somewhat normal in the SJV for most stone fruit cultivars”, reports Sun World stone fruit breeder, Terry Bacon. Peaches nectarines and apricots set well in most regions, however early fruit development temperatures were relatively high, which causes concern for Bacon. “Temperatures during the first 30 days following full bloom are very important for fruit development. When mean temperature is relatively high, then a cultivar’s fruit development period (FDP) is relatively short and this usually results in earlier harvest and smaller average sizes for packout. We’ve also noticed that brix (sugar content) is generally higher in a year with relatively high springtime temperatures”. Spring temperatures this year were not as high as they were in 2004, when ripening times were 10-14 days earlier than normal and fruit sizes were generally smaller. “However we might see FDP shortened by 7 days or so. It shouldn’t cause as many headaches as we had in 2004, but you could definitely see problems with the earliest peach, nectarine and apricot cultivars. I like to see at least 68-72 days FDP for the earliest peaches and nectarines. Even at that you struggle to make the 60’s sizes that US buyers demand. In 2004, many late April-Early May cultivars were picking at 58-62 days FDP because of high springtime temperatures and growers couldn’t get size. This year we expect those same cultivars to be in the 66-70 days FDP range, which is challenging but hopefully not disastrous. Early-to-midseason plum ripening times also may be relatively early, and sizes could be reduced, but Bacon remains optimistic. “Shortened FDP may be off-set this year by natural thinning caused by Mother Nature. Set seems to be light for many of the SJV plums this year and we are not sure why at this time. We had some high temperatures during set, but we also had some light freezes during bloom. Optimistically I am thinking growers will still be able to achieve the numbers they want with far less thinning costs.”

Stone fruit quality

Fruit quality and flavor may be good this year according to Bacon. “We are cautiously optimistic about quality; with a relatively warm spring we could see brix levels up by one or two points. And the SJV has been relatively dry, which is good for nectarine and plum finish and packout. Last year’s record heat wave has resulted in a few more double-fruit in some peach and nectarine cultivars this year, but it doesn’t look too bad really. If we get through it all with no major hail events we may be in very good shape”.

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