Location: National Programs
Project Number: 0500-00082-001-005-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jun 1, 2024
End Date: May 31, 2025
Objective:
The overall objectives of this project are: 1) Determine the reaction of US wheat and barley cultivars and germplasm to newly detected races of Puccinia graminis f. sp. tritici (the causal fungus of stem rust) and Puccinia striformis in Eastern Africa; and 2) Identify new sources of seeding and adult plant resistance to stem rust in improved CIMMYT wheat germplasm and sharing it with US wheat scientists.
Approach:
In order to achieve the objectives, germplasm evaluated from U.S. Cooperators is sent to Kenya both in off and main season each year. Screening activities are carried out during off season (January- April) and main season (June- September), off season nurseries accommodate spring wheat and main season nurseries include winter wheat post vernalization and transplated as hill plots in the field. For stem rust, a mixture of the prevalent Ug99 lineage pathotypes,TTKSK, TTKST, TTKTK, and TTKTT is used with a mixture of susceptible genotypes including “Cacuke”, “Robin”, Kasuko and six lines carrying the resistance gene Sr24. Four rows of spreaders are planted 2 weeks ahead of planting and 4 rows planted alongside nurseries on all four corners of each block with parallel and perpendicular spreaders to create uniform disease pressure. Approx. 5gm of each spring germplasm is planted as twin rows of 70cm, and every two runs of the genotypes with clumps of spreaders inside the nursery to create high disease pressure. Artificial inoculations are carried out at Zadoks 16/18 stages (Jointing) stage by injecting into the plant suspended urediniospores suspended in distilled water using a hypodermal syringe. Syringe incoulations are carried out on three occasions alongside spraying using hand held automizers when early morning dew is expected for successful infection. First round of spreaders initiate infection starting from flag leaf stage and second round of spreaders produce inoculum to continue post flowering soft dough and hard dough stages ensuring continuous supply of inoculum.
