In 2022, the Foundation funded its third round of research projects. A synopsis of the two research projects selected by the Foundation is provided below.
ONE SIZE DOES NOT FIT ALL: THE NEED TO ESTABLISH NEW TREATMENT AND INTEGRATED PEST MANAGEMENT THRESHOLDS FOR BLUE ALFALFA APHIDS (YEAR 2) submitted by Michael D. Rethwisch, UCCE, Riverside County, Blythe
Summary: Currently existing UCCE economic and treatment thresholds for blue alfalfa aphids in California alfalfa were developed when insect pressures were currently less than those recently documented and insecticides were fully systemic, compared with many newer insecticides are which are only acropetally systemic, and when alfalfa prices were much lower than currently being noted. Cowpea aphids are now also major pests in California low desert alfalfa and interactions and integrated pest management (such as ladybeetles) for control from one pest (cowpea aphids) to the next (blue alfalfa aphids) needs investigation, as yellowed alfalfa from cowpea aphid feeding is thought to be more attractive to blue alfalfa aphids migrating into alfalfa fields. This project year proposes continued comparative evaluation of current and potential new insecticides applied at various crop heights to document their efficacy in controlling blue alfalfa aphid, with data to be collected on alfalfa yield, quality and economic values to develop pest management decision tools and treatment/ economic thresholds for California alfalfa growers and pest control advisors on both established and first year alfalfa stands as 2022 data indicate large differences in insecticide efficacy results (which is not included in current thresholds).
EVALUATION OF ALMOND HULL APPLICATION AS A SOIL AMENDMENT TO ALFALFA STANDS submitted by Sarah Light, UCCE Sutter, Yuba, and Colusa Counties, and Rachael Long, Agronomy and Pest Management Advisor, Yolo, Solano, and Sacramento Counties
Summary: Last year, 4-8 tons/ac almond shells were applied to replicated research plots in a three-year old alfalfa stand and data collected on soil health, weed suppression, and alfalfa performance. The 8-ton per acre covering gives a uniform half to one inch covering of shells, which appear to suppress weeds in preliminary visual observations, and which we speculate may contribute to increased soil moisture retention. In year two, more almond shells will be applied to the same replicated field plots (within 6-months the shells assimilated into the soil) and the multi-year impact of almond shell application on the alfalfa stand, weed suppression, and soil health (including moisture retention and compaction) will be measured.
In 2021, the Foundation funded its seconded round of research projects. A synopsis of the two research projects selected by the Foundation is provided below.
ONE SIZE DOES NOT FIT ALL: THE NEED TO ESTABLISH NEW TREATMENT AND INTEGRATED PEST MANAGEMENT THRESHOLDS FOR BLUE ALFALFA APHIDS submitted by Michael D. Rethwisch, UCCE, Riverside County, Blythe and Thomas Getts, UCCE, Lassen County, Susanville, CA
Summary: Populations levels and damage by blue alfalfa aphids have become more damaging in California over the past decade, resulting in significant yield loss in the low desert and often crop death in intermountain regions. Many newer insecticides are only acropetally systemic (they only move to new leaf growth) and do not control aphids below the upper canopy. As such plant/stem height at time of application becomes extremely important for insecticide efficacy which differs by product and rate. This project proposes to evaluate and compare various current and potential new insecticides applied at various specific crop heights to document their efficacy in controlling blue alfalfa aphid. Additionally, information on alfalfa yield, quality and economic values will be collected to provide pest management decision tools and treatment/economic thresholds for California alfalfa growers and Pest Control Advisors (PCAs).
EVALUATION OF ALMOND HULL APPLICATION AS A SOIL AMENDMENT TO ALFALFA STANDS submitted by Sarah Light, UCCE Sutter, Yuba, and Colusa Counties
Summary: California growers are adopting innovative strategies to increase soil carbon and recycle agricultural by-products onto production farmland. Some producers have begun to adopt the practice of adding almond shells and hulls from nearby orchards onto alfalfa fields, however the benefits of this practice to the alfalfa stand have not been quantified. This project aims to measure changes in soil health and alfalfa yield for fields with and without almond hull application.
In 2018, the Foundation funded its first round of research projects. A synopsis of the three research projects selected by the Foundation is provided below.
EVALUATION OF WEED MANAGEMENT IN CONVENTIONAL SEEDLING ALFALFA submitted by Mariano Galla, UCCE Agronomy & Weed Science, Butte and Tehama Counties
Summary: Seedling alfalfa is especially susceptible to weed interference as interspecific competition can inhibit alfalfa growth and development compromising stand persistence. Poor weed control in seedling alfalfa can influence the size of future weed infestations through contributions to the soil seedbank thereby necessitating additional control measures. The research will evaluate the efficacy and safety of herbicides for the management of weeds in establishing stands. Because alfalfa is grown across a variety of environments within the state, concurrent trials will be conducted in the low desert, the San Joaquin and Sacramento Valleys, and the Intermountain area to generate up-to-date performance data specific to major growing areas.
EVALUATION OF WEED MANAGEMENT IN ESTABLISHED ALFALFA submitted by Thomas Getts, UCCE Weed Ecology and Cropping Systems Advisor – Lassen, Modoc, Plumas and Sierra Counties
Summary: Weeds are a significant concern in established alfalfa stands because weed infestation can reduce hay yields. Hay quality can also be influenced by weeds, because of palatability, nutrition, or toxicity concerns. Weeds can interfere with the cutting, curing, and baling processes, or they can trigger load rejections (i.e. noxious weed contamination). Local and export dairy markets pay growers a premium for weed free high-quality hay, whereas hay contaminated with weeds will be worth far less per ton. Weed control in alfalfa is imperative to economical production. The objective of the study is to evaluate the efficacy and safety of herbicides for weed management in established alfalfa fields. Because alfalfa is grown across a variety of environments within the state, concurrent trials will be conducted in the low desert, the San Joaquin and Sacramento Valleys, and the Intermountain Area to generate up-to-date performance data specific to the major growing regions.
REDUCING WEED PRESSURE DURING STAND ESTABLISHMENT USING PRE-PLANT WEED GERMINATION FOLLOWED BY MECHANICAL OR CHEMICAL CONTROL submitted by Sarah Light, UCCE Agronomy Advisor, Sutter, Yuba and Colusa Counties
Summary: Despite evidence that allowing weeds to germinate, and then controlling them prior to planting alfalfa is effective for reducing weed pressure during stand establishment, this practice is not widely used in the Sacramento Valley. This project will evaluate the use of a sterile seed bed, followed by either mechanical or chemical control, to reduce weed pressure during alfalfa establishment in the region. The cost of implementing both control methods will be quantified to enable the clientele to make informed management decisions on their farms.