California tree nuts could be facing a new pest threat with a particular type of beetle. Manager of the California Pistachio Research Board, Bob Klein said the beetle is thought to be Carpophilus truncatus. However, the beetle’s exact species name may change with taxonomic revisions. Klein highlighted the issue during the recent CAPCA Conference in Reno, Nevada. The pest poses a risk as it can be easily mistaken for the dried fruit beetle, which is within the same genus but has less impact on nuts.
“In other countries where it occurs, it is a very serious pest causing up to 10 percent damage on almonds,” Klein explained. “It attacks nuts in the field and lays its eggs on the nut. Then the larvae burrow into the nut, digging tunnels and galleries. So round pinhole type damage on the nut.”
The type of damage it can cause in pistachios is distinct from other pests like navel orangeworm. Concerns about a potential new pest threat arose as industry members reported seeing holes in pistachios. “The holes are not due to navel orangeworm and we have no other pest that we know will burrow holes except this new beetle. So, we’re thinking that that’s what we’re seeing in the nuts,” said Klein.
To address this issue, winter sanitation is proposed as the initial step. Similar to the navel orangeworm, the beetles overwinter in mummy nuts in the field. However, uncertainties remain regarding the timing of the beetles’ emergence in the spring, hindering the ability to schedule effective pesticide sprays. Some sprays used to control navel orangeworm may be effective in late-season applications as hulls degrade. However, materials which specifically target Lepidoptera pests are not likely to have efficacy on the beetle. Tree nut growers are encouraged to be on the lookout for this new beetle pest in orchards.
“Anybody who thinks they’re seeing it in their field should contact Houston Wilson,” Klein explained. “He’s the associate IPM specialist located at the Kearney Ag Center and is leading the efforts on it.”
Brian German
Ag News Director / AgNet West