After 20 years of fruit-tree breeding and 15 years of working with almonds as director of Burchell Nursery’s breeding program, John Slaughter is edging closer to his goal of developing commercially viable self-fertile Nonpareil and California-type almond varieties.
Cross-pollinated varieties depend on bees to transfer pollen from the flower of one variety to the flower on a different variety before fertilization can occur, but a self-pollinating variety can set nuts using the pollen within its own flowers.
“They’re the future of the industry,” says Slaughter, who is based at the company’s breeding program near Fresno. His work with almond and stone fruit takes him throughout the world to areas with climates similar to California.
Theoretically, a self-fertile almond would save growers the expense of renting bees to pollinate a crop. But, that’s not Slaughter’s objective. In fact, he says, bees increase pollination and nut set percentage of self-fertile varieties. He envisions using the self-fertile trees to reduce, rather than eliminate, the need for bees.
“Right now, there’s no better for pollinating flowers than with bees,” Slaughter says. “Instead of requiring a minimum of 14 or 20 frames (2 to 3 hives) of bees per acre, an orchard with self-fertile varieties may need only a fraction of that number. I would like to eliminate bees as the necessity and expense that they currently are, but the data don’t support bee-less practices.”
Self-fertile almond varieties are also more productive when another source of pollen is present. Rather than having an orchard of single, self-fertile trees, he sees growers planting several different self-fertile varieties together.
“You get a better set, with larger kernels and fewer blanks and shrivels, when you utilize pollen from a different variety,” Slaughter says. “I didn’t make that up — it’s well-documented.”
He’s also working to develop self-fertile almond varieties that bloom at the same time and are mature for harvesting at the same time as cross-compatible partner varieties.
“You could harvest all the nuts with one shake, one sweep and one pick up,” he says. “At the same, the nuts have similar physical characteristics so the huller/sheller wouldn’t chip, scar and break one variety while leaving the other untouched. Additionally, one harvest reduces the dust volume of multiple sweepings down the same center.”
In addition to developing self-fertile varieties with desirable agronomic features, Slaughter is focusing on producing the type of nuts that can make money for growers by meeting the demands of the market. This includes traits like nut size, flavor, color and oil content.
He continues to test his self-fertile almonds throughout the state, planting new trials each year. He’s winnowed his 2010 selections down to about 140 varieties that are highly self-fertile.
Slaughter wants to place the trees in every fruiting area of the state so he can assess how they perform at various latitudes, elevations, soils, rainfall, humidity, disease sensitivity, bloom coincidences and chilling hours. He’s also evaluating performance of the trees using different rootstocks, tree spacing and other cultural practices.
“It isn’t enough to have heavy yielding, self-fertile selections,” he says. “They also have to meet utility and industry standards. High, uniform kernel quality, flavor, blanchability, slicing, slivering, roasting, etc., are important components in the commercial requirements.”
“Monoculture is exciting when you consider uniform pruning requirements, the irrigation needs of a single cultivar, knowing exact nutritional inputs and, of course, ‘mono-harvest’,” Slaughter says.
“But the thing I know about California almond growers is that they will always look for improvements. I have great respect for their drive and ethos — it’s why they are where they are now. Improvements in yield, kernel quality, disease resistance, consistent production and lowering input costs are always their challenges. They will deploy and search out the best practices to achieve optimal yields. Count on them.
“That will mean using more than one self-fertile/cross-compatible variety in plantings to approach the vicinity of 6,000 pounds of paid meats per acre. I think breeders need to do their part to equip growers with newer and better tools — that’s what we shoot for.”