Volume: 7 Issue: 9 Date: August 14, 2015 Potato Bytes
Klamath Basin Research and Extension Center 6941 Washburn Way Klamath Falls, Oregon 97603 (tel)541‐883‐4590 (fax) 541‐883‐4596 h p://oregonstate.edu/dept/kbrec Brian A. Charlton, Research and Extension Agent ‐541‐591‐1255 Nichole Baley, Faculty Research Assistant 530‐598‐8533 inch / day
Potato Crop Water Use
Early Planting
0.50
'99‐'14 Avg
0.40
Series2
0.20
Crop Water Use: 1 Soil Degree Data: 2 ,3 Insect Trap Report 4 Notes From Brian 5‐7 Historical P‐day Accumulation
June 1 ‐September 15
0.00
5/15
6/15
7/15
8/15
9/15
Potato Crop Water Use
Late Planting
0.4
inch / day
0.30
0.10
2015
0.3
1999‐2014
Average
0.2
710
700
690
680
670
660
650
640
630
620
610
600
0.1
0
7/5
8/5
Total P‐Day Accumulation
Estimated Emergence ‐ August 13th
9/5
KBREC Actual Water Use: Inches 800
600
Plan ng Date: Early Late Last 3 days: 0.71 0.74 Last 7 days: 1.59 1.65 Last 14 days: 3.31 3.40 Es mated Water Use: Next 7 days 1.68 1.75 p‐days
6/5
Inside this Issue: May 15
400
June 1
June 15
200
0
2011
2012
2013
2014
2015
Volume: 7 Issue: 9 Date: August 14, 2015 Potato Bytes
Klamath Basin Research and Extension Center 6941 Washburn Way Klamath Falls, Oregon 97603 (tel)541‐883‐4590 (fax) 541‐883‐4596 h p://oregonstate.edu/dept/kbrec Brian A. Charlton, Research and Extension Agent ‐541‐591‐1255 Nichole Baley, Faculty Research Assistant 530‐598‐8533 Soil Degree‐Day Accumula on ‐‐ KBREC and IREC 2015 For Root‐knot nematode control, Vydate applica ons should begin at 800 degree‐days (DD5C). To es mate that date, add the number of Total degree‐days "Total" on the day you planted to 800. Where that value occurs in the "Total" column es mates the date on which 800 DD5C will occur in that field. It is recommended that applica ons con nue every 14 days un l harvest. For Stubby‐root nematode control, Vydate applica ons should begin at 0 degree‐days (at plan ng) and followed by an applica on at the first full irriga on following emergence. An addi onal applica on is recommended at 800 degree‐days (DD5C). Volume: 7 Issue: 9 Date: August 14, 2015 Potato Bytes
Klamath Basin Research and Extension Center 6941 Washburn Way Klamath Falls, Oregon 97603 (tel)541‐883‐4590 (fax) 541‐883‐4596 h p://oregonstate.edu/dept/kbrec Brian A. Charlton, Research and Extension Agent ‐541‐591‐1255 Nichole Baley, Faculty Research Assistant 530‐598‐8533 Soil Degree‐Day Accumula on ‐‐ KBREC and IREC 2015 For Root‐knot nematode control, Vydate applica ons should begin at 800 degree‐days (DD5C). To es mate that date, add the number of Total degree‐days "Total" on the day you planted to 800. Where that value occurs in the "Total" column es mates the date on which 800 DD5C will occur in that field. It is recommended that applica ons con nue every 14 days un l harvest. For Stubby‐root nematode control, Vydate applica ons should begin at 0 degree‐days (at plan ng) and followed by an applica on at the first full irriga on following emergence. An addi onal applica on is recommended at 800 degree‐days (DD5C). Volume: 7 Issue: 9 Date: August 14, 2015 Potato Bytes
Klamath Basin Research and Extension Center 6941 Washburn Way Klamath Falls, Oregon 97603 (tel)541‐883‐4590 (fax) 541‐883‐4596 h p://oregonstate.edu/dept/kbrec Brian A. Charlton, Research and Extension Agent ‐541‐591‐1255 Nichole Baley, Faculty Research Assistant 530‐598‐8533 Insect Trap Report
August 4 – August 10
Klamath County
TRAP
1
2
3
4
5
6
7
8
9
LOCATION
Old Hwy. R. Clark
Micka NW 1/4 Pivot
Sutty S of RxR
Hwy. 39 E of Merrill
Spring Lake S of X-Rd
Homedale S of Diversion
S SideBy-Pass
A-B Line A-11
Hwy. 140
PTW
0
0
0
0
0
0
0
0
0
BLH
0
0
0
0
0
0
0
0
0
OLH
21
10
17
10
7
19
21
49
12
OP
0
1
0
0
0
0
0
3
2
PP
0
0
0
0
0
0
0
0
0
0
0
0
N/A
0
0
0
0
0
0
0
0
N/A
0
0
0
0
0
9
15
13
N/A
12
8
71
6
19
0
1
0
N/A
3
3
0
2
1
0
0
0
N/A
0
0
0
0
0
PA
16
4
3
4
0
15
1
1
4
2
12
GPA
0
0
0
0
0
1
0
0
0
0
0
OA
3
0
3
7
0
5
0
1
4
0
20
OP
0
0
0
0
0
0
0
0
0
0
0
PP
1
0
0
0
0
0
0
0
0
0
0
Modoc and Siskiyou
1
2
3
4
5
6
7
8
9
Copic Bay
Panhaldle
South West Sump
Frog Pond
Wright Rd.
101 E. of Rd 111
101 W of Rd. 113
Stateline E of Drain 10
Stateline W of Walsh Rd.
Aphid Traps
1
2
3
4
5
6
7
8
9
10
11
Keno/Warden Rd.
Lower Lake
Malin County Rd. 112
North Malin
Harpold Rd.
Schaupp Rd.
Teare
Bly Mountain
Yonna Drive
Mitchell Rd.
North Mitchell Rd.
PTW: Potato Tuberworm
BLH: Beet Leafhoppers
OLH: Other Leafhoppers
OP: Other Psyllids
PP: Potato Psyllids
PA: Potato Aphid
GPA: Green Peach Aphid
OA: Other Aphids
OP: Other Psyllids
PP: Potato Psyllids
Volume: 7 Issue: 9 Date: August 14, 2015 Potato Bytes
Klamath Basin Research and Extension Center 6941 Washburn Way Klamath Falls, Oregon 97603 (tel)541‐883‐4590 (fax) 541‐883‐4596 h p://oregonstate.edu/dept/kbrec Brian A. Charlton, Research and Extension Agent ‐541‐591‐1255 Nichole Baley, Faculty Research Assistant 530‐598‐8533 Brian’s Notes: Late blight foliage samples collected August 1 have been determined to be strain US‐23. This is the most widely distributed strain in the US. As most of you are aware, we have not had a confirmed late blight infected field in the Klamath Basin since 1998‐2000. Late blight usually survives from year‐to‐year in infected tubers placed into storage, in cull piles, or volunteer potatoes. The water crisis of 2001 likely broke the 1998‐2000 late blight cycles in the Klamath Basin as we’ve enjoyed a 15 year absence of this devasta ng disease. As such, diligent efforts to manage storage rot, cull piles, and volunteer potatoes this fall and next spring are a must! So far, infected fields are largely confined to the Tulelake Lease Lands, although some infected fields are being reported off the Lease Lands. Condi ons remain conducive for late blight and the risk of tuber blight is high especially in fields already infected. Sporula on of this patho‐
gen is favored by moderate temperatures (60‐80oF), high humidity, and frequent irriga on. As you know, these condi ons exist in most every potato field with lush canopy growth and 5‐day irriga on events. Once established, this disease can spread rapidly and if le un‐
checked can defoliate a field in a ma er of weeks. Of more concern, sporangia produced on the foliage are washed down into the soil by irriga on and/or rainfall events reaching tubers and inci ng infec on. The quandary at the moment is a emp ng to protect infected pockets within a field from spreading further as well as protec ng adjacent healthy fields. We have been advising the use of both aerial and chemiga on techniques for applying fungicides. However, excessive irriga‐
on is the main avenue that spores travel from infected foliage to cracks in the soil and subsequently to tubers. Therefore, it is advisable to reduce irriga on dura on and frequency to the greatest extent as possible. This is difficult as crop ET rates are dropping but s ll rela vely high and most fields are in the bulking phase. In short, do your best! Most PCA’s are hesitant to enter fields for fear of poten al spread. As such, you and your staff should be educated on what this disease looks like. Refer to the following YouTuber video: h ps://www.youtube.com/watch?v=uCzIFVfyNow. Addi onally, my July 31 issue of Po‐
tato Bytes has photos taken of infected foliage from the Klamath Basin, and Rob Wilson at UC IREC has some great photos at the following link: h p://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=18682. Be sure to disinfect boots and clothing prior to entering other fields – this is a good prac ce regardless but should be mandatory if leaving infected fields and entering fields where the disease is not yet pre‐
sent. Managing Storage Rot Infected fields should be dug last (if possible) and shipped or processed immediately if at all possible. If storage is required, it is advisable to load these tubers where they can shipped or discarded easily (not at the back of the cellar) if storage rot progresses quickly. Storage facili‐
es should be kept cool as possible (variety specific for processing as some can process well from 45oF and slightly cooler). Tubers should not go into storage wet, and rela ve humidity on suspect fields should be kept as low as possible without exacerba ng pressure bruise. Phostrol, and Storox/Oxidate (hydrogen peroxide/peroaxyace c acid mixture) are registered for control of storage pathogens. I’d suggest you refer to this publica on to review rates, mings, and efficacy on both late blight and pink rot: h p://extension.uidaho.edu/kimberly/
files/2013/11/phostrol05.pdf. It appears Storox/Oxidate are rela vely weak on suppressing late blight infec on in storage compared to Phostrol and other phos acid products. Volume: 7 Issue: 9 Date: August 14, 2015 Potato Bytes
Klamath Basin Research and Extension Center 6941 Washburn Way Klamath Falls, Oregon 97603 (tel)541‐883‐4590 (fax) 541‐883‐4596 h p://oregonstate.edu/dept/kbrec Brian A. Charlton, Research and Extension Agent ‐541‐591‐1255 Nichole Baley, Faculty Research Assistant 530‐598‐8533 Stadium, a newer product from Syngenta Crop Protec on, is a three way mixture of azoxystrobin (Quadris), fludioxonil (Maxim), and dif‐
enoconazole (Inspire). This is an effec ve product for control of Fusarium dry rot and Silver Scurf and can be used to control/suppress these pathogens; however, results from Wisconsin have shown good control of tuber late blight even though this disease is not currently listed on the label. See the following link for data: h p://vegetables.wisc.edu/wp‐content/uploads/2013/02/Post‐harvest‐Fungicides‐for
‐Management‐of‐Storage‐Diseases‐WPVGA‐Mee ng‐February‐6‐2013.pdf. This product is not currently registered for seed potatoes so be sure to read and follow the label. Managing Cull Piles This should be rela vely simple – bury and/or spray cull piles to prevent foliar growth! This should be repeated as o en as necessary to keep the piles dead. I’ve seen far too many ac vely growing cull piles in recent years – negligence as a result of not dealing with late blight the past 15 years. Volunteer Potatoes Suspect fields might benefit from an applica on of MH‐30 to reduce the possibility of volunteer potatoes next year. Despite most fields having the majority of tubers larger than 2.0‐2.5 inches in diameter, this product can be applied 2 weeks prior to vine‐kill. Depending on next year’s crop, there are a host of good products to control potato volunteers. As with most applica ons, efficacy is largely dependent on proper ming of applica on. Please refer to the July 31 issue of Potato Bytes to review specific fungicide op ons and tank‐mix partners. It is also advisable to review the following to help with resistance management (taken directly from Na onal Potato Council website, for full report visit: h p://
www.nwpotatoresearch.com/pr/PDFs/FungicideResistance2009.pdf Avoid resistance by….… Make use of disease predic ve models to effec vely me applica ons of fungicides. Scout fields frequently to monitor for appearance of lesions of early blight and late blight especially when condi ons are conducive For infec on. Prac ce good crop hygiene by elimina on of sources of primary inoculum, e.g. volunteer management, proper cull disposal and maagement of alternate hosts. Use varie es less suscep ble to foliar and soilborne diseases. Monitor and maintain agronomic factors such as soil moisture and crop nutri on to avoid crop stress throughout the season. Where possible, extend crop rota on intervals to avoid increasing inoculum of soil‐borne pathogens. Follow label guidelines for applica on of all fungicides. Labels of newly registered fungicide products include detailed informa on on resistance management along with the Fungicide Group Code (carboxamide fungicides (Endura) belong to Group 7, QoI fungicides b long to Group 11, mancozeb belongs to Group M3, Bravo belongs to Group M5). Volume: 7 Issue: 9 Date: August 14, 2015 Potato Bytes
Klamath Basin Research and Extension Center 6941 Washburn Way Klamath Falls, Oregon 97603 (tel)541‐883‐4590 (fax) 541‐883‐4596 h p://oregonstate.edu/dept/kbrec Brian A. Charlton, Research and Extension Agent ‐541‐591‐1255 Nichole Baley, Faculty Research Assistant 530‐598‐8533 Avoid resistance by….… Group 11 products should be used in 1/3 or fewer of the total number of sprays for the season up to a seasonal limit of six mes. Fugicides belonging to other mode of ac on groups also have product specific use statements on the labels that need to be incorp rated into effec ve disease and resistance management plans. Apply fungicides prior to plant infec on by the fungus and avoid cura ve treatments with QoI and other site‐specific fungicide groups. Never apply back‐to‐back treatments with site‐specific fungicides or fungicides with a medium to high risk of resistance. When disease pressure is high, avoid using site‐specific fungicides such as Group 11 materials. Rotate fungicide applica ons between different mode of ac on groups. For effec ve resistance management, the rota on partner must be ac ve against the target pathogen. Use formulated mixtures or tank‐mixes of effec ve fungicides having different modes of ac on. For effec ve resistance management, both mixing partners must be ac ve against the target pathogen. Use effec ve mul ‐site fungicides, less prone to fungicide resistance, as mixing partners and especially in later parts of the growing season when disease pressure is o en greatest. Be alert for control failures and report control difficul es so that the possibility of resistance can be monitored and evaluated. Local and regional coopera on in resistance management is essen al. How can I tell what group a fungicide belongs to? In 2001, the EPA proposed a pes cide labeling scheme that added the FRAC Mode of Ac on Classifica ons to fungicide labels. In this scheme, all registered pes cides are classified by mode of ac on and each mode of ac on is assigned a group symbol (number or le er). There are currently over 40 groups and more are added as new modes of ac on are discovered or iden fied. Le ers are assigned when the mode of ac on is unknown (U) or mul site (M). For potatoes, 15 groups plus several mul site contacts are registered in the U.S. and currently available for use in disease management programs. Lastly, we have the capability to send suspect foliage off for strain tes ng. Please contact me or Rob Wilson at UC IREC if you have suspect foliage or general ques ons regarding late blight management op ons. Rob also compiled a management checklist that has some great informa on to review and can be accessed at the following link: h p://ucanr.edu/blogs/blogcore/postdetail.cfm?
postnum=18682