Disease Resistance in Collections of Beta Species

Abstract

In a collaborative EU-funded program (GENRES CT95­ 42), up to 600 Beta accessions are being screened for resis­ tance to several important diseases ofsugarbeet (Beta vul­ garis ssp. vulgaris) including beet mild yellowing virus (BMYV), beet yellows virus (BYV), Aphanomyces cochlioides, Pythium ultimum and powdery mildew (Erysiphe betae). Results are promising, with between 0.3 and 16% of accessions exhibiting high levels of resistance. A preliminary analysis ofBMYV,Aphallomyces, and pow­ dery mildew data indicates some differences in disease resistance among Beta types. Early testing of progeny de­ rived from plants highly resistant to BMYV and powdery mildew has shown that these traits are heritable.