Challenges to growing cherries
High salts, low chilling hours, fruit doubling, and low yields test the resolve of cherry growers in California's southern San Joaquin Valley.
In mid-February, these Brooks cherry buds were already starting to push. These cherries are some of the earliest to be picked in California.In mid-February, these Brooks cherry buds were already starting to push. These cherries are some of the earliest to
Prices may be high for the early district cherries of California, but growers there have a host of issues to deal with, including poor productivity.
In the last 15 years, there's been a surge of cherry acreage planted in California's southern San Joaquin Valley, from Bakersfield to Fresno. A strong Japanese export market and new cherry varieties that tolerate the warmer temperatures of the southern San Joaquin Valley have fueled the increase. Growers from northern San Joaquin Valley and even Washington State have planted cherries in the new region to expand their marketing window and join the lucrative, early export market. But the learning curve has been steep as growers are challenged with new issues that come with growing in a new production region and a climate different than the established cherry district in the northern San Joaquin Valley.
At a cherry orchard near Bakersfield which is owned by Kyle Mathison of Wenatchee, Washington, manager Dan Herstand said that high salt levels in the water, low chill units, and high temperatures postharvest are among their biggest challenges.
Mathison has 1,350 acres planted in the area. The first cherries planted, Tulare on Colt rootstock, were planted in 1992 in a small, six-acre block. Since then he has continued to plant cherries: 175 acres in 2000; 230 acres in 2001; and 500 acres in 2003. Varieties include Brooks, Tulare, Early Garnet, Rainier and Royal Rainier, Coral Champagne, Sequoia, Chelan, and Flavor Giant.
Each year, irrigation water pumped from an underground aquifer brings in about 750 pounds per acre of sodium chloride, said Chuy Chavez of Mathison Orchards. "Such high sodium levels have been difficult to deal with and drastically reduce yield."
Chavez explained that the soils were planted to cotton before the cherry trees. "They were abused from the cotton production. We are constantly fighting salts in the pump water and must add N-furic acid to the water all the time." He added that the water that comes from the irrigation district—from the Sierra Nevada mountain snowpack—is fairly clean, but not always available. They treat their pump water with 18 to 20 gallons per acre of N-furic per year.
They annually apply three to four acre-feet of water to the cherries. Water from the irrigation district costs $44 per acre-foot, while pumping costs for groundwater vary between $60 to $80 per acre-foot, depending on the energy source for the pump.
Before the orchard was converted to microsprinklers, they were using about five acre-feet of water by flood irrigating, Herstand said.
Production correlates with the amount of sodium in the soil, Chavez said, noting that they have been tracking yields and sodium levels from different blocks in the last few years. In 2005, the soil was high in sodium—above 600 parts per million—and yields were around half a ton per acre. By 2007, they were able to lower sodium levels, and production increased to about four tons per acre.
"Production has not been near as high as Kyle wants," Chavez said. "Realistically, we need to be getting seven to ten tons per acre. We have to really concentrate on reducing the sodium levels."
Chavez also notes they have worked hard to build up organic matter in the soil. Repeated applications of compost and an application of humic acid have increased soil humus levels to 3 to 4 percent in most blocks, and up to 6 percent in some places. The organic matter was almost nonexistent when they started due to years of cotton farming by the previous owners.
The compost, green waste from Los Angeles, is stockpiled in Arvin for agricultural use. The material has no manure; therefore, it is relatively low in nitrogen. Before fuel prices became so high, the compost cost about $10 per ton, including delivery. Now, the cost is about $19 per ton.
To overcome low chill units and increase the dormancy hours, they run a line for overhead microsprinklers through the trees about 14 feet high. They start the sprinklers in late October, keeping trees wet during the winter to help lower orchard temperatures. Herstand said that keeping temperatures below 45° F for two extra hours each day for a two-month period can significantly increase the chilling hours.
The overhead sprinklers have a dual purpose in June and July when they are also used to prevent cherry doubling. The overhead sprinklers cool down orchard temperatures when buds are differentiating and help control doubling in the next year's crop. With high temperatures in the summer, doubling is a frequent problem for southern San Joaquin Valley cherry growers.
Workers must move the overhead lines back to ground level after bud differentiation, Herstand said, because they found the lines gave too much evaporative cooling and were not effective for summer irrigation.
The rest-breaking agent Dormex (hydrogen cyanamide) is sprayed on about half of the acreage at the Mathison orchard to break bud dormancy after the minimum number of chill hours have been received. Dormex induces earlier and more uniform bloom. Weather station "watch dogs" in the orchard monitor the winter chill hours.
This year, they applied Dormex on January 10 and 11, which means that bloom will follow in 60 days. Harvest is expected to start around April 25, depending on weather. It pays to be among the earliest cherries picked in California—prices for the earliest fruit can be as high as $160 per box compared with $40 per box for cherries picked several weeks later in May.
The Mathison Orchards cherries are picked, precooled, and shipped in a refrigerated trailer to Stockton, some 250 miles north, for packing at Chinchiolo Fruit Company.