|Nyankanga, R - UNIV OF NAIROBI|
|Wein, H - CORNELL UNIVERSITY|
Submitted to: Northeast Potato Technology Forum Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 10, 2007
Publication Date: March 14, 2007
Citation: Nyankanga, R.O., Olanya, O.M., Wein, H.C. 2007. Schematic Models for Potato Tuber Blight Infection Based on Foliar Blight Severity, Cultivar Resistance, Soil and Atmospheric Variables. Northeast Potato Technology Forum Abstracts. Pg. 86 Technical Abstract: Potato tuber blight caused by Phytophthora infestans accounts for significant losses in storage tubers. Despite research on infection and management of tuber blight, there is limited published data on models predicting tuber blight infection or development. We modeled the dynamics of tuber blight infection using foliar blight, cultivar reaction, soil and atmospheric variables and their interactions based on replicated field experiments from two distinct environments of Freeville, New York and Tigoni, Kenya. At Freeville, late blight was initiated by artificial inoculation (US 8 isolate, A2), while at Tigoni, natural blight infections occurred. All isolates at Tigoni were of US 1 genotype (A1). Fungicide applications were scheduled to vary foliar disease levels (control, 25% and 100% rates for Freeville; control, 7, 14, and 21 day intervals for Tigoni). Mean disease levels (AUDPC) were 535-956 and 115-1589 at Freeville and Tigoni locations, respectively. Mean tuber blight ranged from 0.5-40% and 0.3-18% at Freeville and Tigoni, respectively. Path coefficient analysis identified foliar blight, cultivar resistance, tuber depth, soil temperature and rainfall as variables impacting tuber blight. Regression models based on atmospheric, soil variables and cultivars as dependent variables had moderate prediction of tuber blight at Freeville (R2=60%), but low prediction at Tigoni (R2=40%). The infection models for cultivars varied by locations. This research assesses infection pathways and develops models for tuber blight.