Avocados Continued from Page 3
Faber added. “They have just done awful things to not just the crop, but to the trees. It’s actually outright killed young trees. We’ve had no acts of God like that here in the last 12months.” There is one potential issue lurking in the Pacific Ocean: La Niña, which tends topush the stormtrack farther north. This pattern, Faber said, tends to bring “typi- cally low rainfall, which typically reflect low humidity, which means it’s a greater likelihood that we get cold spells. We just need to be on guard for that.” There is no set temperature at which frost becomes a concern; Faber noted the temperatureanddewpoint in the forecast will tell the tale. Dewpoint is the tempera- ture at which the air reaches a relative hu- midityof 100%andwaterdropletsbegin to condense into dew. “You know that when the sun goes down, it could pretty rapidly go from 35 degrees, 34 degrees, boom, down to 26 degrees in just a few hours,” Faber said. “You’re looking at what the potential is for that nighttime temperature.” A solution may lie in overhead sprin- klers, typically used when the thermom- eter is at the other extreme. “It’s not irrigation,” Faber said. “It’s not applyingwater tomeet the transpirational needs, but it’s water applied to the leaves in order to cool them. These techniques can be very, very effective for heat mit- igation, but they could also be used for frost control.”
California avoca- do growers have harvested 263.5 million pounds of fruit this season. Ventura County, seen in 2018, is the top-producing county in the state.
As most of the state is still in extreme or exceptional drought, water may pose a challenge barring a wet winter. Wolk’s home turf, San Diego County, may be in a better spot thanmost; the U.S. Drought Monitor showedmoderate drought in the county as of last week. “Southern California has water,” Wolk said, because “Southern California, over the recent decades, has invested in reli- ability, whichmay not be the case inother parts of the state.” Availability is not the is- sue, he added—“it’s managing the cost of thewater.”Thatmeansbeingmoreprecise
and takingadvantageofmodern irrigation technology, Wolk said. “Today’s sensors are, tome, almost un- believable,”Wolk said. “They sense every- thing—salinity,moisture, the spectrumof the informationyouneedtoirrigate.”Some of these, he added, are tied to computers with preset levels; the water comes on when these levels are reached.Wolknoted that the systems still need tobe checked in the grovemultiple times per week. Water, Faber said, may be the driving force behind avocados’ northerly migra- tion. In 2019—the latest year for which
countycropreportsareavailable—Ventura Countyhad16,491acresofavocadogroves, while SanDiegoCounty had 14,946. “The bulk of it is north of Los Angeles now,” Faber said. “That’s where cheaper water is. That’s the thing about Ventura; there’s a lot of deep groundwater that’s available.”WithSantaBarbaraandSanLuis Obispo counties added, some 70% to 75% ofCaliforniaavocadoproductionnowtakes placenorthof theCityofAngels, Faber said. (Kevin Hecteman i s an ass i s tant editor of Ag Alert. He may be contacted at khecteman@cfbf.com.)
CIMIS REPORT | www.cimis.water.ca.gov
CALIFORNIA IRRIGATION MANAGEMENT INFORMATION SYSTEM
For the week October 21 - October 27, 2021 ETO (INCHES/WEEK)
YEAR
3.0
THIS YEAR
2.5
LAST YEAR AVERAGE YEAR
2.0
1.5
1.0
0.5
0.0
MACDOEL II (236)
BIGGS (244)
DAVIS (06)
MANTECA (70)
FRESNO (80)
SALINAS-SOUTH (214)
FIVE POINTS (2)
SHAFTER (5)
TEMECULA (62)
IMPERIAL (87)
THIS YEAR LAST YEAR AVG. YEAR % FROM AVG.
.37 .63 .54 -32
.35 1.07 .77 -53
.58 .96 .84 -31
.72 .84 .74 -3
.41 .82 .65 -34
.41 1.28 .81 -48
.62 .70 .70 -12
.67 .74 .73 -8
.55 .57 .86 -35
1.16 1.02 1.02 13
W eekly reference evapotranspiration (ETo) is the rate of water use (evapotranspiration—the sum of soil evaporation and crop transpiration) for healthy pasture grass. Multiplying ETo by the appropriate “crop coefficient” gives estimates of the ET for other crops. For example, assume ETo on June 15 is 0.267 inches and the crop coefficient for corn on that day is 1.1. Multiplying ETo by the coefficient (0.26 inches x 1.1) results in a corn ET of 0.29 inches. This
information is useful in determining the amount and timing of irriga- tion water. Contact Richard Snyder, UC Davis, for information on coefficients, 530-752-4628. The 10 graphs provide weekly ETo rates for selected areas for average year, last year and this year. The ETo information is provided by the California Irrigation Management Information System (CIMIS) of the California Department of Water Resources.
For information contact the DWR district office or DWR state headquarters:
SACRAMENTO HEADQUARTERS: 916-651-9679 • 916-651-7218
NORTHERN REGION: Red Bluff 530-529-7301
NORTH CENTRAL REGION: West Sacramento 916-376-9630
SOUTH CENTRAL REGION:
SOUTHERN REGION:
Fresno 559-230-3334
Glendale 818-500-1645 x247 or x243
16 Ag Alert November 3, 2021
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