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less summer precipitation than in the more humid mid-west and eastern U.S. A trial in California comparing organic to convention al production found few differences between the systems, and although trees were slightly smaller, and profitability was greater for the organically-managed orchard (Swezey et al., 1998). In Washington, apple yields under organic management were generally compa rable with non-organic apples in multiyear studies (Peck et al., 2006; Reganold et al., 2001), which explains the relatively greater proportion of organically-grown fruit in that state than in most other U.S. states or Cana dian provinces. Because of increased pre cipitation and humidity that leads to greater disease pressure and more insect pest species present, organic apple production is substan tially more difficult in the eastern U.S. than in drier western states. In a long-term evalu ation of organic apple production in Ver mont, cumulative crop yield was far below economically acceptable conventional yields for nearly all cultivars trialed, and newly es tablished trees were all unprofitable (Brad shaw et al., 2016a; Bradshaw et al., 2016b). In Kentucky, yield in a long-term trial of or ganically-managed, scab-resistant apple cul tivars (SRCs) was substantially lower than what is typical for non-organic, commercial apples in the state, and only 43-64% of fruit were considered marketable primarily due to insect and disease damage (Williams et al., 2015). Evaluation of organic apple produc tion in New York has shown greater success. In one study, the SRC ‘Liberty’ was evaluat ed over four seasons in comparative organic and integrated (a hybrid of organic and con ventional) management systems and overall, organic management was competitive with integrated fruit production for yield and tree growth, although pest incidence was gener ally greater (Peck et al., 2010). In a separate trial that compared two intensities of organic management with a non-treated control in an orchard consisting of multiple SRCs, similar levels of pest and disease incidence to the prior New York and Vermont studies were

observed (Agnello et al., 2017). However, higher prices received for certified-organic fruit would likely offset a lower percentage of clean fruit under organic management, so long as yield is sufficient as outlined by Bradshaw et. al. (2016b). Over the last several years, several new rootstocks have been released from the Cor nell-Geneva breeding program (managed jointly by Cornell University and the United States Department of Agriculture-Agricul tural Research Service). Many of these Ge neva series rootstocks have been previously evaluated in other NC-140 trials (Autio et al., 2013; Autio et al., 2017a; Autio et al., 2020a; Autio et al., 2017b; Autio et al., 2020b; Autio et al., 2011b; Autio et al., 2011c; Marini et al., 2014; Robinson et al., 2007). The objec tives of this current trial were to assess and compare performance of several Cornell Geneva rootstocks managed using organic management procedures at multiple sites in North America. Materials and Methods In spring, 2015, an orchard trial of 10 apple rootstocks was established at 10 sites in North America (Table 1) under the coor dination of the NC-140 Multi-State Research Committee. ‘Modi®’ [a U.S. trademark of ‘CIVG198’(Leis et al., 2008)] was used as the scion cultivar, and trees were propagat ed by Wafler Nursery (Wolcott, NY, USA). ‘Modi®’ is a ‘Gala’ x ‘Liberty’ hybrid SRC bred in Italy. This cultivar was selected for its reported high fruit quality, consistent yield, and resistance to fire blight. Rootstocks in cluded nine named Cornell-Geneva clones [Geneva® 11 (G.11), Geneva® 30 (G.30), Geneva® 41 (G.41), Geneva® 202 (G.202), Geneva® 214 (G.214), Geneva® 222 (G.222), Geneva® 890 (G.890), Geneva® 935 (G.935), and Geneva® 969 (G.969)] and M.9 NAKBT337. The trial was planted in California, Colo rado, Idaho, Massachusetts, Michigan, New Mexico, Nova Scotia (Canada), New York (Geneva and Ithaca), and Vermont. In eight