Kern County Status Report

April 2000

As we begin a new season in Kern County, the goal of the Pest Management Alliance Reduced Input in Almonds Trial is to implement and refine the monitoring techniques we established in 1999. One of the lessons we learned last season was the necessity of vigilant monitoring programs to successfully farm almonds under a reduced input system.

The first thing we monitored in the fall was mummy removal. Navel Orangeworm (NOW) over winters in the mummies that remain on trees after harvest. For this reason, good sanitation is a must. We found some blocks that had more than the allowed two mummies per tree. This simple monitoring practice provided us with the information we needed to request that the grower do additional poling.

We also examined some mummified nuts for NOW larva. This allowed us to see if NOW was present in the orchard. It was interesting to note that there were no complete nuts on the ground, only shells. An early morning visit to the orchard revealed a lot of rodent activity cleaning up the orchard floor.

In early February, we monitored twigs for over wintering San Jose Scale (SJS). This information, along with SJS traps and sticky tapes during the growing season, will allow us to pinpoint the location of any possible SJS outbreaks.

Dormant sprays applied to the conventionally farmed blocks were Lorsban and oil in water, while the reduced input blocks got only oil and water. Due to the wet spring, the entire trial was sprayed with a fungicide mixture of Captan and Benlate.

Our monitoring technique for Peach Twig Borer (PTB) emergence, which was great in 1999, was less than successful this year. For whatever reason, weather, early or late emergence or the age of the trees, we could not find hibernacula. Since this monitoring technique proved unreliable, growers who wanted to apply Dipel sprays would have to rely on bloom to time applications.

We have begun trapping for Peach Twig Borer, Navel Orangeworm and San Jose Scale. SJS biofix was set at March 14th.

We did two soil samplings for web spinning mites in March. Soil gathered at the base of the trees was put in a cup and placed on a sticky card. It was allowed to sit inside for two weeks, then the mites that emerged from the soil and stuck on the card were counted. Once again, this gives us an advanced look at where we may encounter mite problems during the season. We found significantly less over wintering mites in the reduced input blocks. We will begin monitoring for mites on the leaves in April.

We will also begin monitoring the trees for water stress in April. This is done by taking mid-day stem water potential readings. Past studies have indicated a relationship between water stress and pest problems. Disease monitoring has revealed no problems at this time.