Research priorities in our breeding program have changed dramatically since the outbreak of Fusarium Head Blight (FHB) in summer 1993. FHB was present in epidemic proportions again in 1994 and 1995. While it was less severe in 1996, it was a serious problem for all concerned. Breeding for resistance to FHB has become the number one objective.

We have found that the biggest challenge in breeding for resistance to FHB is obtaining field nurseries that permit effective screening. In 1996, we had nurseries at three locations where we applied FHB inoculum and did misting or sprinkling to achieve moisture levels that encourage disease development. To our dismay, FHB infection was too low at one location and excessive at a second location.

We have two rather distinct FHB breeding efforts. We have labeled them fast-track and long-term. If we are fortunate, the fast-track program could lead to a resistant variety in two to three years; the long-term effort will require much longer. The long-term effort relies on resistant germplasm that is later-maturing, two-row type obtained mostly from China. I will not discuss this effort.

In the fast-track program, resistant germplasm was found within the Minnesota program and was part of the effort to develop varieties resistant to kernel discoloration or kernel diseases in general. The FHB resistance was first observed in a Crookston nursery in 1995. In this nursery, a line that we later labeled MNS85 (M92-567) had reduced kernel discoloration compared to the the Stander check and fewer FHB infected kernels and lower toxin level (DON).

MNS85 is the product of a breeding effort that began in 1970, to combine kernel discoloration resistance with favorable agronomic and malting quality traits. The source of FHB resistance is the six-row introduction from Switzerland, Chevron. To date, eight cycles of breeding have been done with each cycle requiring three to four years.

MNS85 has substantially improved kernel discoloration resistance compared to Robust and Stander (Table 1). In 1996, MNS85 was intermediate in yield between Robust and Stander and similar to Foster. In maturity and height, MNS85 was identical to Robust. Plump kernel percentage was high.

Evidence bearing on resistance to FHB in MNS85 is encouraging. In three non-inoculated trials, which may prove to be as useful as inoculated trials for evaluation, percentage of infected kernels was well below the percentage for Robust and Stander (Table 2). These were yield trials and a Chevron check was not included. In three inoculated FHB nurseries in 1996, MNS85 was intermediate between susceptible check varieties and the resistant Chevron in percent infected kernels.

Toxin or DON level in the grain is a critical aspect of resistance in barley and obtaining reliable data on DON may be even more challenging than obtaining reliable data on percentage infected kernels. In 1996, DON level ranged from negligible in some nurseries to over 100 ppm in other nurseries. In three trials, one inoculated and two non-inoculated, DON level in MNS85 was below that in Robust and Stander but the difference was not large. Chevron had the lowest ppm DON in all trials.

Looking ahead, we plan to do extensive testing of MNS85 in 1997. A seed increase in Arizona this winter will make plant scale quality testing possible this summer.

Table 1. Kernel discoloration.

Entrty	Crookston - 1995	St. Paul - 1996
MNS85	1.8?	1.5
Robust	4.3	2.5
Stander	4.0	3.5
Chevron	1.0	1.0

?1=no discoloration, 5=highly discolored.
 

Table 2. FHB severity, non-inoculated nurseries.

	Crookston			Stephen
Entry	1995	Seeding rate trial (1996)?		1996
	---------------------------------------------%-------------------------------------------
MNS85	14	4.0		1.8
Robust	30	9.2		10.2
Stander	46	8.6		9.0

?Lowest seeding rate (four replicates).