Late Blight Confirmed In Areas Of Idaho; Number Of Potato Psyllids Dips
July 31, 2015 Weather conditions, such as rain and cooler temperatures, in Idaho in mid-July have made conditions favorable for late blight and other potato diseases. Potato psyllids, however, have been on the decline in the last week.
On July 17, in south eastern Idaho three fields in Bingham County were noted as having late blight, according to the Pacific Northwest Pest Alert Network. Genotyping of isolates have identified the strain as US-23.
As of July 21, late blight was confirmed in Minidoka County. According to recent posts on the Pest Alert Network, late blight in Minidoka County also is the US-23 strain, which is sensitive to mefenoxam. As a result, growers can use Ridomil Gold pre-packs (e.g. Ridomil Gold Bravo, Ridomil Gold MZ) to manage late blight. Fields which have been treated with mefenoxam appear to be free of late blight even though they are close to fields with confirmed late blight.
Additional fields in Minidoka County have been confirmed, with the latest finds close to Rupert.
Click here for more information on fungicides for managing late blight.
Decline In Psyllid Numbers
On a positive note, the number of potato psyllids in Idaho potato fields declined this week. According to a recent post, 43 psyllids were captured (compared to 71 last week) across the Treasure and Magic Valleys. Psyllids were captured this week from several fields in Ada and Canyon counties, as well as from a few different sites in Elmore and Twin Falls counties. None of the psyllids from last week tested positive for liberibacter (Lso), the bacterium that causes zebra chip.
Click here for more information, including online spreadsheets that show details of the psyllid captures in potato fields over the season.
Source: Pacific Northwest Pest Alert Network
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