Two important topics were addressed by Dr. Nathan Kleczewski, Extension Specialist in Plant Pathology at the University of Delaware this week in the Weekly Crop Update.
- Phytophthora nictotiana, a late blight look-a-like, was found on potato in DE
- Explaining Late blight lineages in relationship to thier potential host and sensitivity to mefenoxam
We have on occasion detected Phytophthora nicotiana on potato in southern New Jersey when wet weather conditions have been prolonged. The good news is that P. nicotiana, although it looks like Late blight, does not show anywhere near the destructiveness that comes with Late blight.
Last week Late blight, Phytophthora infestans, (US23) was found in tomato in Northern New Jersey. US23 has been the predominant genotype found throughout the region during the past few years. Why is knowing the genotype so important? US23 will infect both tomato and potato and has been shown be sensitive or to have intermediate-sensitivity to mefenoxam (i.e., Ridomil Gold). Knowing that US23 is present in New Jersey should put all tomato and potato growers on high alert and everyone should be scouting on a regular basis. All tomato and potato growers should initiate standard protectant fungicide programs if they already haven’t done so.
