Perceptions and Management of Ventenata by Producers in the Inland Pacific Northwest

Ventenata is an annual grass that has invaded agricultural and wildland settings in the Inland Pacific Northwest, causing economic and ecological losses. We know little about producers’ perceived risks and management of ventenata. We present results of surveys in 2011 and 2014 targeting producers across affected counties in Idaho and Washington. Awareness of ventenata and costs to producers increased across that time interval. Respondents attending ventenata Extension events adopted recommended management strategies more than those who did not attend. Our study documents the importance of continued integrated pest management research in concert with stakeholder engagement and education

LEGUME COVER CROPS IN ORCHARDS Results from the 2013 Screening Trial

Falcata alfalfa growing in the d rive row at Tudor Hills Orchard , July 2013. This technical note presents findings from the 2013 Prosser Legume Screening Trial, in which 22 species and cultivars of potential legume cover crops were evaluated in three orchard environments. Section 1 is a summary of key points that can be printed and read independently. Section 2 contains study details

Legume Cover in Orchard Drive Alleys

Orchardists in Washington State are interested in finding an alternative source of nitrogen to offset the need for commercial fertilizer, which can be expensive, difficult to transport and apply, and may cause reductions in soil pH and fruit quality. Previous studies suggest legumes grown as drive alley cover may be able to supply up to 50% of the nitrogen requirements of an orchard, however a more extensive evaluation of legume species and varieties was necessary. An assessment of 25 different legumes was conducted in three apple orchards in the Yakima River Valley in south-central Washington. Legumes were planted in 100 ft long plots in drive alleys at each site and evaluated two to four times per year for three years. Measurements taken include percent establishment, percent cover, plant height, percent biomass nitrogen, and biomass and nitrogen production. An economic analysis was also conducted to determine the value of the nitrogen contribution in both organic and conventional orchards. Alfalfa varieties had higher percent cover (50 to 100%), more biomass (2,500 to 4,500 DM lb/ac/yr) and biomass nitrogen production (80 to 180 lb N/ac/yr) than the clover and other legume species. Alfalfa biomass nitrogen was significantly higher than clover biomass nitrogen in three out of four site x year combinations. Economic analysis showed after three years of production in an organic orchard, the alfalfa varieties, some white clover varieties, and 'Dominion' red clover had the potential to compensate for their establishment costs with the value of nitrogen they produced. Some alfalfa varieties also compensated for establishment costs in a conventional orchard. INTRODUCTION Organic and conventional orchardists in Washington rely on external sources of nitrogen, which can be expensive, labor intensive and sometimes result in lower soil pH or increased salinity and reduced fruit quality (Stamatiadis et al., 1999; Hoagland et al., 2008). Legumes grown in orchard drive alleys may provide a more sustainable, less expensive, on-farm source of nitrogen. In a previous study, a 4 foot wide legume strip in the drive alley was able to supply approximately 50% of the nitrogen required by the orchard, and increased levels of plant-available nitrogen were detected in the tree row following " mow and blow " management (Davenport and Granatstein, 2010). Four legumes were evaluated in that study; they include: kura clover (Trifolium ambiguum M. Bieb), 'Ladino' white clover (Trifolium repens L.), birdsfoot trefoil (Lotus corniculatus L.), and alfalfa (Medicago sativa L.). A more extensive screening of legumes was needed to determine the ideal species and cultivars that have the potential to supply nitrogen. The objective of this trial was to evaluate a broad spectrum of legume species and cultivars for their ability to thrive in an orchard environment and provide a significant nitrogen contribution

THE POTENTIAL FOR LEGUME COVER CROPS IN WASHINGTON APPLE ORCHARDS A Discussion and Literature Review

Crimson clover growing in the drive row of a mature apple orchard near Prosser, WA, May 2013. The purpose of this Technical Note is to discuss the potential for legumes to supply an orchard's nitrogen needs. Section 1 is a summary of key points that can be printed and read independently. Section 2 contains an in-depth literature review

Monitoring Uptake of Legume N by Apple Tree Using Nitrogen Isotope Discrimination

Intercropped legumes can supply nitrogen to fruit trees and reduce the need for purchased nitrogen fertilizer, potentially reducing costs and environmental footprint. The project evaluated nitrogen isotope techniques (comparing the 15 N and 14 N signal from the legume N versus other sources) to monitor the degree of uptake by apple trees of legume N grown in the orchard. The project involved two components: 1) a greenhouse study using 15 N-labeled clover residue added to potted apple trees to quantify legume-N uptake and a comparison to values using nitrogen isotope natural abundance; 2) a field study in an existing orchard legume cover crop trial using natural abundance for a qualitative evaluation of legume N and the ability to detect this signal in an ambient field environment. The 15 N enrichment technique is known to be more sensitive than the natural isotope abundance technique, but is not suitable for routine field use by growers or consultants. The objective of the project was to determine the uptake of legume-derived N in a quantitative manner and compare it with a more qualitative method to assess its utility on farms. Lower tree leaf 15 N atom% with legume alleys versus grass was detected in several instances in both trials, indicating that the natural isotope abundance method does have potential use for monitoring the timing of legume uptake by trees. PROJECT DESCRIPTION Objectives. Trial 1. Compare legume-N uptake by potted apple trees using the 15 N enrichment technique versus the natural isotope abundance technique. Trial 2. Monitor natural isotope abundance of legumes, soil, and apple trees in an existing legume cover crop trial to determine the magnitude of the signal difference in the different orchard components. Methods. Trial 1 was repeated using potted trees under shade cloth outdoors, after the initial trial (2014) was compromised by saline water in the greenhouse. Trees ('Golden Delicious'/B.9) were planted on 9 April 2015 in 20 " diameter pots filled with virgin Warden silt loam soil (no history of cropping). Forty-five trees were planted; 20 for each phase of the trial, with 5 extras. The trees were grown through the 2015 season without treatment due to the lack of enough 15 N labeled clover, and then they were placed in cold storage for the winter. There was not enough labeled 'Alice' white clover biomass to do spring 2016 treatments either, so trees and clover were grown through the summer. Fall treatments were applied on 9/13/16 to 20 trees. Prior to this, soil samples (0-10 ") and tree leaves (10 per tree) were collected for a pre-treatment baseline. All trees had received a Hoagland's nutrient solution during 2015 and 2016 in order for them to grow, and there appears to be a small amount of 15 N enrichment in this material tha