Root and crown, or foot root rots are important diseases of cereals worldwide, particularly in the dryland areas of the WANA (West Asia and North Africa) region where cereal rotations under sub- optimal growing and rainfed or limited irrigation conditions predominate. Dryland root rots generally include a complex of species such as common root rot (Bipolaris sorokiniana (syns. Helminthosporium sativum, H. sorokinianum, Teleomorph Cochliobolus sativus (Ito &Kurib.) Dresch. ex Dast.", and several species of crown root (Fusarium spp.). The two most reported Fusarium species are F. pseudograminearum (formerly F. graminearum Group I, Teleomorph Gibberella coronicola) and F. culmorum, while several others, such as F. acuminatum, F. avenaceum and F. crookwellense, have also been reported. Yield loss caused by these cereal root pathogens have been documented in many regions ofthe world, including Europe, America, particularly in more marginal cereal production areas of West Asia, North Africa, Australia and Canada (1,4) to be between 3-50% ( 1 ). Considering the similarity of cropping patterns and climate with those practiced in WANA, soil-borne pathogens in some areas of Central Asia are likely to cause important economic losses, in particular under rainfed and limited irrigation conditions. Cereals, especially wheat and barley, are main crops in Turkey in terms of production and consumption. 51% of sown area and 61% of total field crop area is occupied by wheat. The Turkish research organization GDAR (General Directorate of Agricultural Research) began a Nationwide Wheat and Barley Root Rots Project in 1999 in collaboration with CIMMYT for implementing winter wheat breeding programs in Turkey and the region. Objectives of the joint Turkey/CIMMYT Project: a) survey to identify pathogens of the root and crown rot in the cereal growing regions of Turkey; b) yield loss studies; c) control measures, including: I) resistant and tolerant cultivars; 2) rotation and cultivation systems; 3) chemical options as seed fungicides; 4) effect of microelements A survey of over 450 plant samples from the plateau has implicated the Fusarium species F culmorum and F pseudograminearum to be the main causative agents of dryland root rot. Yield trials on winter wheats inoculated by Bipolaris sorokiniana, Fusarium culmorum ve Fusarium pseudogra- minearum registered yield losses up to 45%. Decreased tolerance was reported in triticale>barley > bread wheat > durum wheat. Several tolerant lines were identified. Similarly, under inoculated field conditions, 7167 genotypes (lines/varieties) ot bread and durum wheat, barley and triticale were tested, over 200 of them being marked for further testing, approval and subsequent integration into the Intemational Winter Wheat Improvement Program. Simultaneously, these lines were sent to CIMMYT Mexico for incorporating into the spring wheat germplasm. Seed treatment with different fungicides increased yield as compared with the control, however their use is limited because if their economic unfeasibility. The application of Zn and Fe microelements was found to be highly important in reducing the losses from dryland root rots; however, variety specific reactions were evident. The current evidence justifies the use of an integrated pest management approach to these dryland root rots with an emphasis on host plant resistance The paper provides a summary of the project implementation outcomes with an, emphasis on the strategy for identifying and incorporating host resistance for controlling these cereal root rots.

Global Wheat Program

English

0407|AGRIS 0401|AL-Wheat Program

Juan Carlos Mendieta

INT0599|INT2410

CIMMYT Staff Publications Collection