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Pesticide Collection for Malheur County
All Crops Treasure Valley - Oregon
Posted on: September 22, 2015 by Bill Buhrig
Great news for Malheur County! There will be a pesticide collection for unwanted/expired materials on October 23rd at Ontario Sanitary Service. Please see the attached brochure for details and the registration form to fill out. Feel free to just register by your first name. The registration process is just for logistical purposes so we know how much is expected to come in. Give us a call at 541-881-1417 if you have questions. We will be happy to help you scan or fax your stuff in. Tell your neighbors as well. We do not know how often these collections will occur in the future.
Update of potato psyllid monitoring in Idaho
Potato All Locations
potato psyllids
Posted on: September 19, 2015 by Erik Wenninger
Abundance of potato psyllids in potato fields in Idaho appears to be lower than last week, with 85 total psyllids captured on sticky cards and vacuum samples thus far (versus 139 captured last week). Several of our “Intense” cards from the Treasure Valley will be processed Monday next week and updated results will be posted at the links below. Captures came from the following counties: Canyon, Ada, Owyhee, Gooding, Twin Falls, Jerome, Minidoka, and Cassia.
Many of our sites, including nearly all of the “Light” sites have been vine killed or harvested and will no longer be sampled.
None of the psyllids that were captured last week was positive for liberibacter (Lso), the bacterium that causes zebra chip, though a few psyllids remain to be tested.
Potato psyllid captures from our bittersweet nightshade sites in the Treasure Valley that arrived late last week were markedly lower than the previous fortnightly sample, with only 4 psyllids found (this is in contrast with the 54 psyllids that we reported on capturing in the Magic Valley sites).
As always, we encourage growers and crop consultants to scout for symptomatic plants and to consider the risk level this year when making insecticide decisions through the remainder of the season.
Photos of typical ZC symptoms exhibited by foliage and tubers may be found here:
http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
Consult our website for more information, including management recommendations and 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 liberibacter testing results come in.
http://www.uidaho.edu/extension/news/psyllid-management
» http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
Fall Garden Pests Remain Active
All Crops All Locations
Aphids and Beet Leafminer
Posted on: September 17, 2015 by Ariel Agenbroad
The weather is cooling off, but some insect pests are enjoying a resurgence in the garden.
Watch your fall brassica crops like cabbage, kale and broccoli for new generations of aphids, they are flourishing in the cooler temperatures. Spray any insects off with a stream of water or use an insecticidal soap.
Also watch for leafminer damage in your late season spinach, beets and Swiss Chard. Removing and disposing of any affected leaves is the best strategy at this point in the season. For next year, use a protective row cover to keep the flies off their favorite crops!
For more information on both of these pests, visit the links below.
» http://hortsense.cahnrs.wsu.edu/Public/FactsheetWeb.aspx?ProblemId=189
» http://hortsense.cahnrs.wsu.edu/Public/FactsheetWeb.aspx?ProblemId=188
Idaho State Department of Agriculture Pesticide Disposal Program
All Crops All Locations
Posted on: September 17, 2015 by Jerry Neufeld
Idaho State Department of Agriculture just released their fall 2015 pesticide disposal program schedule for Twin Falls, Gooding and Nampa. Click on the pdf below for more information.
ZC-positive plants found in potato field in Power County, Idaho
Potato All Locations
zebra chip
Posted on: September 16, 2015 by Erik Wenninger
Tubers sampled from a field in Power County tested positive for liberibacter (Lso), the bacterium that causes zebra chip.
We have found some potato psyllids in our monitoring fields a few miles away from this site, although no psyllids collected from this area have tested positive for Lso so far this year.
As always, we encourage growers and crop consultants to scout for symptomatic plants and to consider the risk level this year when making insecticide decisions through the remainder of the season.
Photos of typical ZC symptoms exhibited by foliage and tubers may be found here:
http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
Consult our website for more information, including management recommendations and 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 liberibacter testing results come in.
http://www.uidaho.edu/extension/news/psyllid-management
» http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
Potato psyllid abundance similar to last week.
Potato All Locations
Potato Psyllid
Posted on: September 11, 2015 by Amy Carroll
Abundance of potato psyllids captured on sticky cards in potato fields in Idaho was similar to last week, with 139 total psyllids captured. Captures came from the following counties: Canyon, Ada, Owyhee, Gooding, Twin Falls, Jerome, and Minidoka counties . In addition, we found 8 nymphs and 4 eggs across three fields in Gooding, Jerome, and Twin Falls counties.
Several more fields have undergone vine kill and are no longer being sampled.
None of the psyllids that were captured last week was positive for liberibacter (Lso), the bacterium that causes zebra chip. A few psyllids remain to be tested. None of the psyllids that remained to be tested at this time last week was positive for Lso.
Some sticky cards have yet to come in this week. As these samples are processed, we will post updated results at the links below.
Psyllid abundance from our fortnightly bittersweet nightshade sampling appears to be up this week. We found a total of 54 potato psyllids (48 from vacuum samples and 6 from sticky cards) across three of our four Magic Valley sites (the Twin Falls Park site is temporarily inaccessible due to construction). Samples from our Treasure Valley sites just arrived and are still in process.
We continue to encourage growers and crop consultants to scout for symptomatic plants and to consider the typical late-season surge in psyllid abundance when making insecticide decisions through the remainder of the season.
Photos of typical ZC symptoms exhibited by foliage and tubers may be found here:
http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
Consult our website for more information, including management recommendations and 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 liberibacter testing results come in.
http://www.uidaho.edu/extension/news/psyllid-management
» http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
Potato psyllid abundance increased; a few more Lso-positive psyllids
Potato All Locations
potato psyllids
Posted on: September 4, 2015 by Erik Wenninger
Abundance of potato psyllids captured on sticky cards in potato fields in Idaho was about 50% higher this week than last with 149 total psyllids. Captures came from Canyon, Ada, Owyhee, Elmore, Gooding, Twin Falls, Jerome, Blaine, and Cassia counties. Several fields have undergone vine kill and are no longer being sampled.
Four of the psyllids that were captured last week were positive for liberibacter (Lso), the bacterium that causes zebra chip. These were from Canyon (one psyllid from each of three different fields) and Owyhee counties.
With the summer winding down and much of our crew having dispersed back to school, we are running a bit behind on leaf and vacuum samples (last week’s results are posted below; only one psyllid was found in a vacuum sample). We expect to complete these next week at which time we will post at the links below.
From our bittersweet nightshade sampling last week, we found a total of 22 psyllids among Treasure Valley and Magic Valley sites; this is about 50% lower than our previous fortnightly sample.
We continue to encourage growers and crop consultants to scout for symptomatic plants and to consider the late-season increase in psyllid abundance when making insecticide decisions through the remainder of the season.
Photos of typical ZC symptoms exhibited by foliage and tubers may be found here:
http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
Consult our website for more information, including management recommendations and 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 liberibacter testing results come in.
http://www.uidaho.edu/extension/news/psyllid-management
» http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
Creating Habitat for Pollinators and Beneficial Insects Farm Tour
Announcements All Locations
Posted on: September 1, 2015 by Jennifer Miller
Contact:
Jennifer Miller, 208-850-6504, Northwest Center for Alternatives to Pesticides
Creating Habitat for Pollinators and Beneficial Insects Farm Tour
Farmers interested in increasing pollinator and beneficial insect habitat on their farms are invited to attend a farm tour at Purple Sage Farms in Middleton, Idaho on Wednesday, September 16.
Purple Sage Farms, the Northwest Center for Alternatives to Pesticides (NCAP) and The Xerces Society will host the tour from 2 to 5 pm.
Tim and Mike Sommer of Purple Sage Farms grow certified organic herbs, greens and specialty produce in their greenhouses, low tunnels and in-field production. The Sommers also raise grass-fed sheep and cattle, an important part of the nutrient cycling on the farm and from which they make their own compost.
Jessa Kay Cruz, senior pollinator conservation specialist with the Xerces Society, will discuss her work with farmers establishing habitat for pollinators and beneficial insects. She will give an overview of pollinators and beneficial insects, their habitat requirements, steps to assessing existing habitat, and organic methods of site preparation for establishing habitat.
The Sommers are working with NCAP and The Xerces Society to incorporate additional pollinator and beneficial insect habitat on their 50-acre farm. They are currently conducting different methods of organic site prep, prior to planting starts into hedgerows this fall. The farm also supports pollinators and beneficial insects through annual plantings, cover crops and allowing production areas to reach flowering.
The tour will conclude with refreshments and a presentation on a new crop insurance program, Whole-Farm Revenue Protection, which provides an opportunity for specialty crop and organic producers to secure risk coverage.
The cost is $20 and pre-registration is required. Register online at www.pesticide.org or contact Jen Miller (jmiller@pesticide.org or 208-850-6504) by September 10.
This tour is made possible by support from USDA Natural Resources Conservation Service Conservation Innovation Grant and USDA Risk Management Agency Education partnership funding. This is an equal opportunity event.
The Northwest Center for Alternatives to Pesticides (NCAP) works to protect community and environmental health and inspire the use of ecologically sound solutions to reduce the use of pesticides.
Potato psyllid abundance similar to last week
Potato All Locations
potato psyllids
Posted on: August 29, 2015 by Erik Wenninger
Total abundance of potato psyllids captured in potato fields in Idaho was similar to last week, with the highest overall numerical count we’ve recorded this year from sticky traps: 102 total potato psyllids. Captures came from Canyon, Ada, Owyhee, Elmore, Gooding, Twin Falls, Jerome, Cassia, and Power counties.
Two of the psyllids that were captured last week were positive for liberibacter (Lso), the bacterium that causes zebra chip. These were from Gooding and Minidoka counties.
With the summer winding down and much of our crew having dispersed back to school, we are running a bit behind on leaf and vacuum samples and on samples from bittersweet nightshade. We hope to have these completed early next week. Leaf and vacuum sample results will be posted at the links below when completed.
We regret to report that there was a problem with some of the liberibacter samples that we sent to campus to be tested a few weeks ago. These were rerun, and it turns out that incidence was lower than previously reported. Corrected liberibacter incidence can be found on the spreadsheets linked below. In spite of this, risk of ZC appears to be higher this year than during the previous two, given the higher abundance of potato psyllids and the presence of liberibacter in psyllids earlier in the season. Therefore, we continue to encourage growers and crop consultants to scout for symptomatic plants and to consider this risk level when making insecticide decisions through the remainder of the season.
Photos of typical ZC symptoms exhibited by foliage and tubers may be found here:
http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
Consult our website for more information, including management recommendations and 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 liberibacter testing results come in.
http://www.uidaho.edu/extension/news/psyllid-management
» http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
Liberibacter-positive tuber found in Idaho potato field
Potato All Locations
zebra chip
Posted on: August 25, 2015 by Erik Wenninger
One of the tubers that was sampled recently from a field in Ada County tested positive for liberibacter (Lso), the bacterium that causes zebra chip (ZC). The sample was taken from one of our “Intense” sites that has seen a relatively large number of liberibacter-positive psyllids. Both foliar and tuber symptoms have been difficult to find in this and other fields that we’ve inspected, so at least in these fields, overall ZC incidence appears to be low.
Nevertheless, risk of ZC appears to be higher this year than during the last two, especially in the Treasure Valley, so we continue to encourage growers and crop consultants to scout for symptomatic plants and to consider this risk level when making insecticide decisions through the remainder of the season.
Photos of typical ZC symptoms exhibited by foliage and tubers may be found here:
http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
Consult our website for more information, including management recommendations and 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 liberibacter testing results come in.
http://www.uidaho.edu/extension/news/psyllid-management
» http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
Potato psyllid abundance increased again this week; a few more Lso-positive psyllids
Potato All Locations
potato psyllids
Posted on: August 21, 2015 by Erik Wenninger
Total abundance of potato psyllids captured in potato fields in Idaho increased about 50% relative to last week; most of this increased abundance occurred in the Treasure Valley. We captured 97 psyllids on sticky cards in fields across the Treasure and Magic Valleys, including fields in Canyon, Ada, Owyhee, Elmore, Gooding, Twin Falls, Jerome, and Minidoka counties. We also found a psyllid on a card submitted to our lab from Power County. In addition, we found a total of seven potato psyllid nymphs from leaf samples collected two different fields in Gooding and Jerome counties.
Two of the psyllids collected last week from potato fields tested positive for liberibacter (Lso), the bacterium that causes zebra chip. Also, two psyllids that we collected in vacuum samples from bittersweet nightshade in Shoshone Falls Park in Twin Falls tested positive for liberibacter.
Risk of zebra chip appears to be higher this year than the last two, especially in the Treasure Valley, so we continue to encourage growers and crop consultants to scout for symptomatic plants and to consider this risk level when making insecticide decisions through the remainder of the season.
Photos of typical ZC symptoms exhibited by foliage and tubers may be found here:
http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
Consult our website for more information, including management recommendations and 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 liberibacter testing results come in.
http://www.uidaho.edu/extension/news/psyllid-management
» http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
Black Mold on Onion
Onion Treasure Valley
Black Mold of Onion - Aspergillus niger
Posted on: August 21, 2015 by Stuart Reitz
Black mold has been found in some early harvested onions in the Treasure Valley.
Black mold is caused by the fungus Aspergillus niger. This disease can develop in the field or during storage. The predominant symptom is a black discoloration of tissue. Infected bulbs may show blackening at the neck, streaks or spots of black fungal spores on or beneath the outer scales, and black discoloration in bruised areas.
Bulbs usually get infected by the fungus through wounds, especially through the neck as onions mature and tops fall over or are cut. The fungus is common in the soil and on dead plant material and spores can readily spread through the air.
Therefore, keeping bulbs in good condition will help prevent disease development.
It is critical to promptly and adequately dry bulbs after harvest so there is not too much moisture in the necks to promote disease development. Remember, warmth and moisture favor disease development.
It is also important to avoid wounding and bruising when bulbs are harvested, transported, or stored.
Storing bulbs at low temperatures (35°F to 55°F) and low humidity helps to control black mold if the bulbs have been cured properly.
Handouts from the Late Blight Management Meetings
Potato All Locations
Late blight
Posted on: August 20, 2015 by Jeff Miller
Meetings were held in American Falls and Idaho Falls on August 18 focused on providing information on late blight management in potato. PowerPoint handouts from those meetings are attached here. The first reviews management in the field up until harvest. The second discusses storage management. The third discusses vine kill as it relates to late blight management.
» Managing Late Blight Late Season
2015 Idaho Association of Plant Protection Annual Meeting
All Crops All Locations
Posted on: August 20, 2015 by Jeff Miller
This is a call for presentations for the 2015 annual meeting of the Idaho Association of Plant Protection in Jerome, ID at the Best Western Sawtooth Inn and Suites. The meeting will be held Wednesday, November 4 from 1:00 pm to 5:00 pm (registration starts at 12:30) and Thursday, November 5 from 8:00 am to 12:00 pm. Please consider contributing research results, observations, unusual disease occurrences, topics which could be discussed as a group, etc. to the meeting. Each presentation will be allotted a 20 minute time slot. Please let us know if you feel you would need more or less time. A final program will be advertised in early October. Registration begins at 12:30 p.m. on Wednesday and the program will begin at 1:00 p.m. Registration costs $15.00 and can only be made by check or cash. Certified Crop Advisor (CCA) and Pesticide Recertification credits (ISDA) will be available.
Hotel reservations at the Best Western Sawtooth Inn can be made by calling 208-324-9200. Indicate you will be attending the IAPP meetings. Regular rooms are available at the corporate rate of $69.99 + tax, but reservations must be made prior to October 12.
Please reply by email or complete and return the bottom half of the attached sheet. If you are not attending this meeting but would like to be notified of future meetings, please send us your updated contact information. Responses can be sent to either Erik Wenninger at erikw@uidaho.edu or Trent Taysom at trent@millerresearch.com.
Canyon SCD Tour
Announcements Treasure Valley - Idaho
Posted on: August 19, 2015 by Jerry Neufeld
The Canyon County Soil Conservation District is holding its 6th Annual 319 Tour of Best Management Practices on August 25, 2015. Click on the pdf below for more details.
Clarification on late blight meeting
Potato All Locations
Late blight
Posted on: August 14, 2015 by Jeff Miller
The previous alert did not specify the locations for the late blight management meetings:
American Falls at the American Falls High School Auditorium - Tuesday, August 18 from 10:00 am -12:00 pm
Idaho Falls at the University of Idaho (Tingey Administration Building auditorium) – Tuesday, August 18 from 1:30 pm – 3:30 pm
Managing Late Blight Going into Storage
Potato All Locations
Late blight
Posted on: August 14, 2015 by Jeff Miller
Please note that the American Falls meeting outlined below replaces the meeting planned for Aberdeen!
The University of Idaho and Miller Research are sponsoring a meeting on managing late blight going into storage. The meeting agendas are as follows:
American Falls - Tuesday, August 18 from 10:00 am -12:00 pm.
Idaho Falls – Tuesday, August 18 from 1:30 pm – 3:30 pm
Dr. Jeff Miller will speak first and discuss proper disease identification, pathogen life cycle and biology, disease management considerations in the field, and appropriate use of fungicides late season through vine kill.
Dr. Nora OIsen will discuss post –harvest fungicide use and selection and proper storage management considerations.
Two ISDA recertification credits are available.
potato psyllid update
Potato All Locations
potato psyllids
Posted on: August 14, 2015 by Erik Wenninger
Abundance of potato psyllids captured in potato fields in Idaho is up slightly from last week. We captured 63 psyllids on sticky cards in fields across the Treasure and Magic Valleys, including fields in Payette, Canyon, Ada, Owyhee, Elmore, Gooding, Twin Falls, Jerome, and Cassia counties. In addition, we found one potato psyllid nymph on a leaf sample from a field in Gooding County.
All of the psyllids collected last week (cards deployed during the week of July 26 and collected during the week of August 2) tested negative for liberibacter (Lso), the bacterium that causes zebra chip.
We captured 43 psyllids from our fortnightly bittersweet nightshade sampling around the Treasure and Magic Valleys. This also is up slightly from the previous samples.
We collected tubers this week and last from several fields that have had the highest incidence of liberibacter-positive psyllids. Foliar symptoms were mostly lacking and, although most tubers examined were clean, a few were found with apparent zebra chip (ZC) symptoms. These samples are being tested for liberibacter, which is the only way to determine with certainty whether or not the plants actually have ZC.
Although all psyllids collected last week were negative for liberibacter and tuber samples that we have examined have been mostly clean, the level of liberibacter found in psyllid samples from Canyon and Ada counties during recent weeks suggests that risk of ZC may be higher in this area. Therefore, we encourage growers and crop consultants to scout for symptomatic plants and to consider this risk level when making insecticide decisions through the remainder of the season.
Photos of typical ZC symptoms exhibited by foliage and tubers may be found here:
http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
Consult our website for more information, including management recommendations and 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 liberibacter testing results come in.
http://www.uidaho.edu/extension/news/psyllid-management
» http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/30058/pnw633.pdf
new layout for PNWPestAlert.net
Announcements All Locations
Posted on: August 14, 2015 by Jerry Neufeld
We are excited to announce a new look and added functionality for the PNWPestAlert.net website. We have been busy this summer, working with our programmer to change the look of the website, as well as adding some additional functions. In a few days we will change over to the new webiste and begin using it. We are also adding content area for “Landscapes and Gardens”. This area of the website will be administered by Ariel Agenbroad, Area Extension Educator for Food Systems & Small Farms with University of Idaho Extension. On the new homepage, you will now see three categories for Alerts: Current Alerts will show all Alerts posted to the website; Crop Alerts will show only Alerts related to agricultural crops; and Landscape and Garden Alerts will show only Alerts related to urban landscapes and garden environments. Current subscribers do not need to do anything different to continue to receive your chosen alerts. However, if you would like to make changes to your user profile or sign up to receive “Landscape and Garden” alerts, you can do that by clicking on “Edit User Profile” (lower left hand side on the new home page) and then make any desired changes to your profile.
We hope you enjoy the new look and functionality of the website and bear with us while we get the bugs out of the new system (no pun intended). If you encounter any issues with the new site, please contact us at jerryn@uidaho.edu or ariel@uidaho.edu and we will address your concerns as soon as possible.
Jerry Neufeld
Ariel Agenbroad
Late blight management meeting
Potato All Locations
Late blight
Posted on: August 14, 2015 by Jeff Miller
A meeting on managing late blight going into storage will be held at the Aberdeen High School on Tuesday, August 18 at 10:00 AM. Speakers will be Dr. Nora Olsen (University of Idaho) and Dr. Jeff Miller (Miller Research). Call Jeff at 208-431-4420 for more information.
Malheur Exp. Station Onion Variety Day
Onion Treasure Valley - Oregon
Posted on: August 14, 2015 by Bill Buhrig
Please join us for the annual Onion Variety Day at the Malheur Experiment Station outside of Ontario on August 25. Tour the plot in the morning and catch lunch as well! It will be a good time!
Check out the attached PDF for more information!
More late blight samples
Potato All Locations
Late blight
Posted on: August 14, 2015 by Jeff Miller
Late blight had been confirmed in additional counties. Positive samples were confirmed in Madison, Fremont, and Jefferson counties yesterday and this morning. Two samples have also been confirmed in Cassia County - one on the east side an another on the west.
Late blight in Cassia, Madison, Fremont, and Jefferson Count
Potato All Locations
Late blight
Posted on: August 13, 2015 by Jeff Miller
Late blight had been confirmed in additional counties. Positive samples were confirmed in Madison, Fremont, and Jefferson counties yesterday and this morning. Two samples have also been confirmed in Cassia County - one on the east side an another on the west.
Potato Diseases Update
Potato Eastern Idaho
late blight, early blight, white mold, bacterial stem rot
Posted on: August 8, 2015 by Phillip Wharton
In the Treasure Valley area Dr. Mike Thornton reports that they are primarily seeing white mold, bacterial stem rot and early blight. The crop is beginning to senescence in some fields, and growers should be carefully monitoring soil moisture to make sure they match water applications to crop use.
In the rest of southern and south eastern Idaho conditions remain favorable for late blight. With the current frequent rain showers and thunderstorms moving through the area and cooler night time temperatures growers should be very vigilant for late blight. In the past two weeks, Dr. Jeff Miller has reported that most of the late blight out breaks have been spread by the thunderstorms moving through the area. This is evident by the uniform levels of disease spread throughout infected fields instead of in isolated infection points or at the edge of fields spreading inwards.
In the past week, the University of Idaho has confirmed 4 more positive infections in Power county and two more in Bingham county but none in Minidoka county. To date, the late bight out breaks appear to be limited to these three counties. All isolates from these outbreaks have been identified as the US 23 genotype and mefenoxam (Ridomil) sensitive.
As we move towards harvest, growers affected by late blight need to be aggressive in managing the disease at the end of the season and going into storage. Growers should be aware that in addition to attacking foliage, late blight can infect tubers at any stage of development before and after harvest and in storage, with symptoms and rot usually only showing up in storage. Late blight infection of tubers is characterized by irregularly shaped, slightly depressed brown to purplish areas on the skin. These symptoms may be less obvious on russet and red-skinned cultivars. A tan to reddish-brown, dry, granular rot is found under the skin in the discolored area, extending into the tuber usually less than half an inch. For more information and photos of late blight tuber symptoms see the attached link (http://bit.ly/1KWFt6a).
Late in the season it is advisable to avoid excessive irrigation as tubers become infected with late blight when spores wash down through the soil from infected leaves. Vines should also be killed at least two weeks before harvest, especially in blight infected fields. This interval minimizes the chance of tubers getting contaminated with late blight inoculum during harvest, and allows previously infected tubers to decompose in the field. If blight is present in the field or in the vicinity of the field at harvest, it may also be beneficial to spray foliage after vine killing with labeled fungicides to kill living late blight spores on the foliage.
For more detailed information on a late season checklist for managing late blight and fungicide fungicide recommendations see the attached link (http://bit.ly/1Kb3ELg).
For up to date information on potato diseases in Idaho and across the country follow us on twitter. http://www.twitter.com/potatodiseases
Late blight update
Potato All Locations
Late blight
Posted on: August 8, 2015 by Jeff Miller
Late blight is spreading in several locations in southern Idaho. Please see the attached "Late blight update" for a summary of the epidemic and an overview of control measure. We have also attached a review of fungicides available for late blight control along with a checklist for managing late blight going into storage.
Links to web pages from the University of Idaho and Miller Research with additional information are listed below.
» http://www.millerresearch.com/alerts/pest-alerts/item/49-late-blight-management-2015
» http://www.idahopotatodiseases.org/lateblight.html
