25 September 1998

Virus difference worth exploiting

KNOW which form of barley virus you are up against before choosing a variety.

That is the message emerging from massive varietal responses in Arable Research Centre winter barley trials.

"We have seen some staggering differences in the performance of some varieties, particularly Fanfare," says ARC director, Mike Carver.

Although Fanfare is not mosaic resistant and yields poorly on land infected with the so-called mild form of the disease, it has done remarkably well at a yellow mosaic-ridden site (see table). Other non-resistant varieties performing in similar vein in the HGCA-funded trials include Rifle and Puffin.

All three recommended resistant varieties, Gleam, Epic and Muscat, yielded well over three years on the mild site. But where yellow mosaic is known to be the problem Epics output in particular has slipped.

Non-resistant Regina and Intro do relatively well on the mild site but also succumb when up against yellow mosaic. "Fanfare shows the symptoms of yellow mosaic but is apparently not adversely affected," says Dr Carver. Breeders initial screenings for resistance do not distinguish between the two common forms of mosaic disease, he notes.

The trials highlight the importance of determining infections on ones own land, says Dr Carver. "Far too often the disease is misdiagnosed as manganese deficiency."

Some fields may contain both mosaic viruses and waiting in the wings is race 2, another strain against which no current varieties are resistant.

lIn total 35 varieties were evaluated for ARC members in 1998 and the results published in the Midland Bank sponsored Descriptive List in mid August. &#42

Winter barley ratings* on

ARC sites with barley

mosaic virus

Mild Yellow

Gleam 118á Fanfare 113.2

Epic (R) 106.8 Vertige 107.9

Muscat 105.9á Rifle 101.5

Intro 105.7 Gleam 101.3á

Regina 102 Muscat 101.2á

Vertige 100.9 Fighter 99.8

Angora 98.1 Intro 99.6

Pastoral 87.3 Puffin 95.6

Rifle 84.6 Pastoral 94.9

Fanfare 82.3 Epic 94.8á

Fighter 77.3 Regina 94.0

Halcyon 77.2 Halcyon 91.6

Puffin 71.2 Pipkin 88.6

Pipkin 64.2 Angora 86.2

*3yr mean (except Vertige 2yr).

á = resistant.