New barley variety intended for planting after Clearfield

 By Kevin Murphy

Barley is well known for the positive benefits it brings to winter wheat rotations. Spring barley is an early maturing crop that uses less water than wheat and can break up predominant disease cycles, often to the benefit of winter wheat. With the surge in acreage planted to Clearfield® winter wheat varieties over the past decade, suitable spring barley ground has diminished substantially. Why? Because traditional spring barley varieties are not tolerant to imazamox herbicides and therefore cannot be grown following a Clearfield winter wheat that has been sprayed with an imazamox herbicide.

Of the approximately 1.9 million acres of winter wheat planted in Washington State in 2016 (2016 Washington Wheat Variety Survey), imazamox resistant varieties including ‘ORCF-102’, ‘Mela’ and ‘Curiosity’ were planted on over 350,000 acres. It is unclear how many of these acres were actually sprayed with Beyond® herbicide and a significant percentage of these acres are located in non-traditional spring barley growing regions.  However, if spring barley were planted on ground following sprayed Clearfield winter wheat, the most likely scenario is that the barley would germinate, grow to the two to four leaf stage, and then die off two to three A person pointing at grainweeks after planting. So in a nutshell, approximately 200,000 acres that may have been suitable for a barley crop in the rotation following winter wheat are no longer available for barley production.

Enter ‘Survivor’, a new two-row, spring feed barley tolerant to the commonly sprayed herbicide Beyond®, part of the Clearfield herbicide tolerant system. Survivor’s origins began when Dr. Steve Ullrich and his PhD student Hyejin Lee used sodium azide to develop over 2 million variations on the commonly grown spring barley variety ‘Bob’ through mutation breeding. Mutation breeding is a commonly used, non-GMO breeding technology employed by barley breeders around the globe. Of these 2 million seeds, Ullrich and Lee identified one with resistance to imazamox, the active ingredient in Beyond® and where the ‘IMI’ abbreviation originates. Over the next few years, seeds from this plant were crossed with Bob, and then backcrossed again with Bob. In between each crossing event, thousands of progeny from these crosses were sprayed in the field and in the WSU greenhouse spray chambers and evaluated for imazamox tolerance. Breeding lines with imazamox tolerance were then tested repeatedly at Spillman Farm in Pullman and subsequently in multiple locations across eastern Washington and selected for grain yield, stripe rust resistance, plump kernels, high protein and overall strong agronomic characteristics.

The first imi-tolerant barley variety released through this program is Survivor. As a spring cereal grain in the Palouse, Survivor is not intended to be sprayed with imazamox herbicide. It is also important to note that the label does not permit spraying on barley. The variety is meant solely as a variety that can withstand residual imazamox herbicide in the field following winter wheat. For growers who have raised Bob in the past, they will recognize many similar agronomic characteristics. But our work does not end with Survivor. Like the popular TV reality show with multiple series, we are working toward a suite of imi-tolerant varieties that will address the current and future needs of Washington barley growers.

Thanks to funding from the Washington Grain Commission and the Robert Nilan Endowment, there’s more to come, a Survivor Series if you will. Survivor is a feed barley, and we have hundreds of feed barleys in the breeding pipeline that will improve upon Survivor in the next few years. We also have thousands of breeding lines derived from dozens of distinct populations that will address malting barley and food barley needs. To give you a quick snapshot of our herbicide tolerant breeding program, in 2017 we sprayed over 18,000 distinct F4 lines, along with susceptible (Bob) and resistant (Survivor) check varieties with Beyond® at four times the labeled rate, nine days after seeding in the herbicide spray chamber in the new WSU greenhouse. Five to seven days after cutting, the seedlings were assessed for IMI resistance: the susceptible seedlings had no re-growth, while the resistant seedlings had re-growth. The resistant seedlings were then transplanted into flats and grown to maturity in the greenhouse. Of the 18,182 plants sprayed, 15,125 were found to be resistant and 3,057 were susceptible. Over 3,600 F5 headrows were grown in 2017, all of which were resistant when sprayed in the field (see Figure 1 for a photo of the susceptible check Bob and the resistant check Survivor).

Where do we go from here and what can you next expect in the Survivor Series? In 2017 we planted our first advanced yield nursery containing our best malt, food, and feed breeding lines with tolerance to imazamox (Figure 2). We expect to include the top lines from this nursery in upcoming variety testing nurseries, and perhaps have our next varieties ready for release in two to three years. We continue to fast track this research using molecular markers and winter nurseries in Arizona in order to get these new varieties to growers as quickly as possible.

In the meantime, if you have ground with residual imazamox herbicide and would like to grow barley, give Survivor a try! Limited pounds of Survivor will be available in the spring of 2018 as Foundation Seed, so contact your seed dealer about planting this new variety next spring.