Besides the weather, Edstrom offers another plausible reason for last year’s malady. Saturated soils were common in the orchards; a combination of spring rains and unnecessary irrigation.

“Some growers irrigated as usual despite the spring rain,” said Edstrom who also manages the Nickels Soil Laboratory in Arbuckle. “Some growers routinely irrigate at specific times of the season or when foliage reaches a certain maturity level on the tree.”

Edstrom convinced growers to reduce irrigation to 50 percent to 60 percent of normal during the summer months on the effected trees. No negative tree symptoms developed afterwards.

Another overlying factor is the clay and silt soils in the Sacramento Valley which are prone to retaining higher moisture levels which reduces oxygen in the soil.

Krymsk86 is of Russian origin and was brought to the United States by USDA. The University of California-Davis propagated the rootstock with the help of the nursery industry. Edstrom was among the first farm advisors to plant Krymsk86 in the early 2000s in different locations.

Today, Krymsk86 rootstock is widely popular in California almond circles.

“Krymsk is a hot item right now; growers are clamoring for the rootstock,” Edstrom said.

Among the rootstock’s top selling qualities is its excellent compatibility with Nonpareil, California’s top-planted variety. Some other existing plum rootstocks have problematic or incompatibility issues with Nonpareil.

“The compatibility of Krymsk86 with Nonpareil looks almost too good to be true,” Edstrom said. “The compatibility is nearly perfect.”

Also, Krymsk86 lacks the negative characteristic of plum suckering at the tree base often associated with other rootstocks. Edstrom has not witnessed any union etch issues in Krysmk86.

“Kyrmsk86 has more vigor than many other plum rootstocks,” Edstrom noted.

California nurseries have sold Krymsk86 like hotcakes. The rootstock is currently planted on tens of thousands of acres across the Sacramento and SJV valleys.

Another selling factor is Krymsk86’s strong, deep root system. High winds in the Sacramento Valley over the last decade uprooted or damaged tens of thousands of almond trees; many on the Lovell peach rootstock. Some rootstocks combined with root or crown diseases led to the increased tree vulnerability in high winds.

“Krymsk86 offers good anchorage for the trees,” Edstrom explained. “Krymsk86 is one of the strongest rooting trees in the California almond industry today.”

Its Superman-strong root system is partly tied to high tensile strength which makes the Krymsk86 bulkier, extensive root system harder to break, compared to weaker rootstocks including Lovell and Nemaguard.

While Krymsk86 appears to be a good rootstock for California’s almond industry, experienced nurserymen contend that 10 to 20 years under widespread planting is necessary to fairly evaluate any rootstock.

For now, Edstrom is not very worried about the problem found last spring. If there is a tie to Krymsk86, the farm advisor says it is an issue that growers can work around.

“After all, the larger issue is to develop an overall orchard canopy and not the problems of a few trees,” Edstrom said.