An integration of agronomy and breeding to reduce disease susceptibility in fall rye
1) Evaluate fusarium head blight, leaf and stem rust in fall rye cultivars. 2) Select disease resistant lines for crossing in Canadian germplasm. 3) Evaluate the timing of fungicide for FHB on fall rye.
Fusarium head blight (FHB) is a common disease in cereal crops, such as wheat, barley, and oat. Very little is known about FHB on rye in Canada. In this project, fall rye spike samples were collected from naturally infected fall rye fields in Manitoba. Five Fusarium species were isolated and identified from these samples. Among them, F. graminearum was the most prevalent Fusarium species causing FHB on rye in Manitoba and was the most aggressive species among the five Fusarium species evaluated on six fall rye genotypes under the controlled environment. Seventy rye lines were assessed through artificial inoculation during multiply field seasons at two locations, Winnipeg and Carman. Field Fusarium head blight disease symptoms, Fusarium-damaged kernels (FDK) in the grain, and deoxynivalenol (DON) concentrations produced by F. graminearum were measured to evaluate rye lines for FHB resistance. Some open-pollinated fall rye lines, such as Anna, Antelope, Florida401, Kustro, Musketeer, Oklon, Prima, Protector, SM4R, Syn20L, Toivo, Visa, and Voima, showed more resistance than other lines. Many hybrid lines had FHB resistance with extremely low disease severity. Although the hybrids tended to have much lower ergot severity than the open-pollinated lines, ergot infection was still a problem for fall rye hybrids. Fungicide timing for managing FHB on rye was investigated through six treatments, including heading, 10% anthesis, 80% anthesis, six days after 50% anthesis, the inoculated-untreated control, and the uninoculated-untreated control. Fungicide applied at 10% anthesis resulted in a significantly lower FHB level than the inoculated-untreated control. Fungicide treatments also significantly increased thousand kernel weight (TKW), test weight (TW), and yield, and reduced ergot severity under a high disease conditions. Leaf rust is another important disease in cereal crops. The reaction of seventy rye lines to leaf rust was evaluated in the rust nursery through artificial inoculation with inoculum collected from naturally infected fall rye fields. Disease severity and infection types were assessed on the leaf when the symptoms were well developed. Most of the open-pollinated lines were moderately susceptible or susceptible to leaf rust. Only a few open-pollinated lines and some hybrids had low disease levels. The combined FHB and rust reaction information identified resistant lines that breeders can use to develop new varieties with these traits. Several hybrids showed moderately resistance or resistance reactions to leaf rust with very low FHB disease severity. Hybrids could be an optimum option for fall rye growers to manage FHB and rust disease on their farms. Data from FHB and leaf and stem rust nurseries were used for selecting resistant parents and in crossing to develop FHB and leaf and stem rust resistant populations for which are being advanced as hundreds of half-sib progenies in the breeding pipeline for eventual release as new OP Fall rye cultivars after registration process.