Registration of Early Flowering Downy Mildew Resistant Triploid Hop Pollinators 1 (Reg. Nos. 9, 10, 11, 12)

EARLY flowering female hop (Humulus lupulus L.) cultivars such as 'Fuggle' in Oregon frequently are only partially pollinated due to inadequate synchronization of flowering time with males. In previous publications, the feasibility of using triploid pollinators for yield stimulation of female hop cultivars was demonstrated (Haunold 1975; Haunold and Nickerson 1979). Eight medium-early to late flowering triploid pollinators, respectively, were found to be best suited for pollinating medium to late flowering female hop cultivars under Oregon conditions (Haunold et al. 1979). The present paper describes four early flowering triploid pollinators — USDA 21189M, USDA 21190M, USDA 21191M, and USDA 21192M — that are suitable for stimulating early flowering diploid hop cultivars to produce higher cone yields in western Oregon. The four pollinators originated from open-pollinated seed collected in 1970 from an open-pollinated seedling of the early flowering triploid hop genotype USDA 56008. They are sibs of four triploid hop pollinators registered previously as Reg. No. GP 10 to 13 (Haunold et al. 1979). All have been tested in nursery plots near Corvallis, Ore. since 1973 and in commercial Oregon Fuggle yards since 1978. They are vigorous monoecious, mostly male genotypes that produce ample amounts of pollen from late June to about mid-July in western Oregon. USDA 21189M and 21192M typically produce sidearms 60 to 100 cm in length. The sidearms of USDA 21190M generally are somewhat shorter (50 to 75 cm), while those of USDA 21191M normally vary from 30 to 60 cm in length. All produce good secondary and tertiary laterals with ample amounts of pollen that is easily dispersed by wind. The four genotypes are resistant to crown infection by hop downy mildew caused by Pseudoperonospora humuli (Mij. et Tak.) G.W. Wils. (Table 1), as judged from field performance in 2-hill nursery plots near Corvallis, Ore. since 1973 and in replicated greenhouse tests under high inoculum levels. Some downy mildew symptoms have been noticed occasionally in early spring before pruning, which probably originated from buds near the soil surface that had been infected in late summer of the pre-