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Late blight

Potato     
July 28, 2015 by Jeff Miller

The late blight in Minidoka County has been determined to be the US-23 strain. This strain 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.

More information on fungicides for managing late blight can be found at the link below.

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Zero positive potato psyllids from last week

Potato     
July 24, 2015 by Amy Carroll

Overall abundance of potato psyllids in potato fields in Idaho this week continued to decline, with 43 psyllids 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. We are still waiting on a shipment of sticky cards from our “Light” sites (approximately 20 fields) in Cassia and Minidoka counties.

Zero psyllids from last week tested positive for liberibacter (Lso), the bacterium that causes zebra chip—one each from Canyon, Ada, and Minidoka counties.

We continue to urge growers and crop consultants to have an IPM program in place and to supplement our monitoring program with their own local monitoring.

Consult our website for more information, including online spreadsheets that show details of the psyllid captures in potato fields over the season. Updates to these spreadsheets may occur throughout the week as Lso testing results come in.

http://www.uidaho.edu/extension/news/psyllid-management

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corn earworm

Corn     Treasure Valley - All
Canyon county, Idaho
July 23, 2015 by Jerry Neufeld

I checked the corn earworm traps today. I found a few, but not too many. Below are the counts.

Location 7/16 7/23

Melba Area 0 0
South of Nampa 0 0
Middleton Area 0 0
Parma Area 0 0
Wilder Area 0 16
Homedale area 0 2
Pride Lane 0 0

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More late blight in Minidoka County

Potato     
July 22, 2015 by Jeff Miller

Late blight had been confirmed in two additional fields in Minidoka County. It is likely in several others. Pathogen spread is likely with current weather conditions. Growers are encouraged to report additional finds so that the extent of infection and rate of spread can be documented.

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Potato Pest Management Field Day

Potato     
July 21, 2015 by Jeff Miller

Miller Research will be holding a pest management field day on Thursday, August 13 at the Miller Research facility located near Acequia, ID (426 E 200 N). A short presentation will be given in the office followed by a tour of the research plots.

The presentations will focus on and chemical management of diseases and will highlight research which has been funded by the Pacific Northwest Potato Research Consortium. We have requested 3 ISDA pesticide recertification credits and 3 CCA (Pest Management) credits for this meeting.

Lunch will be provided. Please RSVP to Jeff Miller by August 10 at 208-531-5124 or by email at: jeff@millerresearch.com so that we can get an accurate count for room preparation purposes.

See the attachment for additional details.

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Late blight in Minidoka County

Potato     
July 21, 2015 by Jeff Miller

Late blight has been positively identified in Minidoka County. It appears the infections resulted from a spore shower and it is likely that other fields are also affected. It is critical for growers to scout fields. Affected fields should be sprayed on a 7-day schedule. If thundershowers persist, a 7-day schedule is advised for all in the area. Management guidelines are available at the link below.

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Weekly Potato Disease Update

Potato     Eastern Idaho
July 17, 2015 by Phillip Wharton

Potato diseases are starting to pick up across the state with the recent wet weather. Dr. Mike Thornton reports that in the Treasure Valley area, there were locally heavy rains associated with thunderstorms much of the past week with some hail damage in a few isolated areas. Cooler temperatures, when combined with the rain are favorable for diseases such as late blight, white mold and aerial stem rot (with hail damage). As such field men should be vigilant and fields should be scouted on a regular basis and growers are urged to apply protectant fungicides.

In the Magic valley early blight and white mold is on the increase due to recent rain showers. Again, due to the weather growers should be vigilant for signs of late blight.

In south eastern Idaho there are currently three confirmed fields in Bingham Co. with late blight. Genotyping of isolates have identified the strain as US 23. It is imperative that field men and growers bring in any suspected late blight samples to the university offices at Idaho Falls or Aberdeen for confirmation and so that we can monitor the late blight strains causing the epidemic. A knowledge of the strains involved in the outbreak will allow us to make better fungicide recommendations to growers. All sample origin information will be kept confidential with only the county of origin being reported.

Since the strains from the current outbreak in Bingham county are US 23, we are dealing with a mefenoxam sensitive strain of late blight. The most effect product for the control of mefenoxam sensitive late blight strains is Ridomil Gold Bravo. Ridomil has been shown to have curative properties and may halt a late blight epidemic if it is applied early enough in the outbreak (less than 1% field infection). Do not use Ridomil if you don't know what strain you have in your crop, as most other strains of late blight are resistant to Ridomil.

In fields where only a few random late blight lesions have been found evenly distributed throughout field (0 - 1% foliar infection), an application of Ridomil Gold Bravo should be made followed by a systemic fungicide such as Revus, Forum, Curzate 60DF, Ranman, Tanos, Gavel or Previcur Flex 5 - 7 days after the first application. The field should then be monitored closely until the end of the season and protectant fungicide applications (EBDC or Chlorothalonil products) made every 7 days until harvest. A late season application of Gavel has been shown to provide additional protection from tuber blight.

In infected fields with one or more (up to 5) loci spreading from the edge of the field or from several centers within the field (1% overall field infection but locally heavily infected plants 5 - 10%), infected areas should be destroyed with Reglone or a similar vine killing herbicide. Destruction of infected areas within the crop with late blight should follow the rules that 30 rows either side of the newest lesions at the border of the late blight locus and 100 feet along the row (either side) are killed with Reglone or with Gramoxone. Although harsh, research has shown that the latent period between infection and symptom development is about seven days and although not visible plants within this area are already infected. An application of Ridomil Gold Bravo should then be applied as above and followed by an alternative fungicide 5 days later. Protectant fungicide applications should then be made every 7 days until harvest.

For more detailed information on late blight fungicide recommendations see the attached link (http://bit.ly/1LfZtmW)

For up to date information on potato diseases in Idaho and across the country follow us on twitter. http://www.twitter.com/potatodiseases

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Potato psyllid numbers dip; more positive psyllids from last

Potato     
July 17, 2015 by Erik Wenninger

Overall abundance of potato psyllids in potato fields in Idaho this week generally were considerably lower than the previous week, which may have been due to the cooler temperatures. Psyllids were captured this week in Canyon, Owyhee, and Elmore counties, as well as from several different sites in both Jerome and Twin Falls counties. We are still waiting on a shipment of sticky cards from our “Intense” sites in Canyon and Ada counties.

Three psyllids from last week tested positive for liberibacter (Lso), the bacterium that causes zebra chip—one each from Canyon, Ada, and Minidoka counties.

Psyllid captures also were lower at our bittersweet nightshade sites around the Treasure and Magic valleys.

We continue to urge growers and crop consultants to have an IPM program in place and to supplement our monitoring program with their own local monitoring.

Consult our website for more information, including online spreadsheets that show details of the psyllid captures in potato fields over the season. Updates to these spreadsheets may occur throughout the week as Lso testing results come in.

http://www.uidaho.edu/extension/news/psyllid-management

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corn earworm

     Treasure Valley - All
Canyon county, Idaho
July 17, 2015 by Jerry Neufeld

I checked the corn earworm traps yesterday and did not find any corn earworm adults. Below are the general locations of the traps.

Melba Area
South of Nampa
Middleton Area
Parma Area
Wilder Area
Homedale Area
Pride Lane

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What is the Pacific Northwest Pest Alert Network?

This website utilizes a network of growers around the Pacific Northwest. As information about pest infestations becomes available, registered users will receive updates pertaining to the specific crops that they may be growing at the time.