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United States Department of Agriculture

Agricultural Research Service

Research Project: ENHANCING SUSTAINABILITY OF FOOD PRODUCTION SYSTEMS IN THE NORTHEAST Title: Effectiveness of SIMBLIGHT1 and SIMPHYT1 models for predicting Phytophthora infestans in the Northeastern United States

item Olanya, Modesto
item Honeycutt, Charles
item Tschope, Beate -
item Kleinhenz, Benno -
item Lambert, David -
item Johnson, Steven -

Submitted to: Archives of Phytopathology and Plant Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 23, 2012
Publication Date: August 30, 2012
Citation: Olanya, O.M., Honeycutt, C.W., Tschope, B., Kleinhenz, B., Lambert, D.H., Johnson, S.B. 2012. Effectiveness of SIMBLIGHT1 and SIMPHYT1 models for predicting Phytophthora infestans in the Northeastern United States. Archives of Phytopathology and Plant Protection. 45:1558-1569.

Interpretive Summary: Predicting when late blight occurs would be helpful for managing this devastating disease. We evaluated several models for predicting late blight outbreak. All models predicted late blight occurrence too early. However, one model, called ‘NOBLIGHT’ accurately recommended fungicide application prior to blight occurrence. None of the simulation models evaluated could account for external sources of inoculum, so this is an area where usefulness of such models could be substantially improved.

Technical Abstract: Accurate prediction of Phytophthora infestans outbreaks is crucial for effective late blight management. The SIMBLIGHT1, SIMPHYT1, and modified SIMPHYT1 models were assessed for predicting late blight outbreaks relative to the NOBLIGHT model using climatic data from field experiments at Presque Isle, ME. The dynamics of late blight infection pressure and Phytophthora efficiency (pew-values) were computed by the SIMPHYT3 model to assess conduciveness of climatic conditions for disease development. The SIMPHYT1 model recommended fungicide applications to commence on July 11, 21, 8, 10, 7 and 7 in 2004, 2005, 2006, 2007, 2008, and 2009, respectively. The modified SIMPHYT1 model (US version) recommended fungicide applications for July 11, 22, 8, 19, 7, and 7 in the same years. Model simulations of disease outbreak differed from actual recorded observations in untreated plots by 24-65 days. The NOBLIGHT model was accurate in forecasting the timing of first fungicide application for disease control. However, it appears significant improvements could result if such models are modified to account for external sources of inoculum.

Last Modified: 11/30/2015
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