Control of Early and Late Potato Blight Experiences and views from practice in Denmark. Agrochef Henrik Pedersen AKV Langholt

Transcription

1 Control of Early and Late Potato Blight Experiences and views from practice in Denmark Agrochef Henrik Pedersen AKV Langholt

2 Start skimmel i Nordjylland 2011 AKV Langholt Starch factory Northern part of Denmark App ha starch potatoes Crop rotation: Three or more years free of potatoes from 2016 Main varieties: Kuras (60%) Kardal (15%) Phytoftera Start 2011 Yellow = infection from soil Red = single soil infection

3 Start skimmel i Nordjylland 2011 Danish Support System Available for all at Additional: Weekly telephone conference: Advisory center, local advisors University Starch industry Improvement and implementation the Danish support system - Project : Aarhus University (Flakkebjerg and Foulum), DMI and the starch industry (KMC and AKV)

4 AKV Counseling 1-2 times a week by to all farmers Strategy: a. Treatment once a week b. Start: When the first infection is seen in some fields in DK Treatment: a. Normal weather: a. ½ dose Ranman/Revus b. In august also Shirlan b. High risk weather a. ¾ dose Ranman/Revus or b. ½ dose Ranman/Revus + Cymoxinil c. Infection in field (or neighbour field) a. ½ dose Ranman/ Revus + 2 l Proxanil (propamocarb+cymoxanil)

5 Development over the last 20 years Period (app.)..app Base chemical Dithane (Mancozeb) (possibly metalaxyl) Shirlan - ½ or ¾ (or full dose) (possibly metalaxyl) Ranman or Revus ½ or ¾ (or full dose) (possibly metalaxyl) Amistar Ranman/ Revus and Shirlan again Proxanil 2012 Highly increased use of Amistar, Signum and.. Variation in interval Some protection against Alternaria Weekly treatment based on meteorological data Some protection against Alternaria Weekly treatment No protection against Alternaria in phytoftera treatment

6 Tool 1: Infection Pressure Infection pressure: Average of daily risk hours for 5 days - 2 previous days, today and forecast for coming 2 days Tool: Infection Pressure - Main use today - Define periods with high risk or low risk of infections - Pedagogically easy to understand - Possible to communicate to a high number of farmers - Give a basically better protection than treating by flair

7 Tool 2: Daily Risk Daily risk: Hours with temp.> 10 C and RH > 88% Tool: Daily risk: - Possible to optimize : Best treatment for today (cymoxinil) - Possible to optimize: Shorter or longer interval - Almost only for individual use

8 Today: Conditions of treatment are more important than choice of dose Movement of the boom Wind speed Irregular fields with curves All corners every time Higher dose near trees Check for nitrogen and infection by phytoftera and Alternaria!

9 Trial - Phytoftera Strategier 1) Stivelseskartofler Kartoffelskimmel, pct 2) Bladplet, pct. 2) Behandlingspris, kr. pr. ha. Stivelse, pct. hkg knolde pr. ha Udb. og merudb. hkg stivelse pr. ha nettoudb., kr. pr. ha forsøg 19 fs 1. 1/1 dosis af 3, , /2 dosis af 5, , Small infection with phytoftera has almost no influence on the yield in starch potatoes, but a big impact on the financial result

10 Alternaria in practice The big Challenge You don't know when it appears and when the treatment should start Our trial results from last year are already outdated The resistance against Azoxystrobin, Pyraclostrobin and boscalid increase every year Trials without artificial infection often show very little yield-effect from treatment In practice we see fields with low influence from Alternaria, and fields which simply die in a short time

11 AKV Strategy Alternaria App. date Interval High risk areas Middle risk areas 1-10/7 X Low risk areas 15-25/ days X X 1-10/ days X X X 15-25/ days X X X Difenoconazol : g Signum (pyraclostrobin+boscalid)

12 Vildmosen 2016 Variety: Folva

13 Vildmosen 2016 Variety: Folva

14 Vildmosen 2016 Variety: Folva

15 Vildmosen 2016 Variety: Anouk Variety: Folva

16 Future? Photo 16. September 2015 Treated Kuras Untreated Nofy

17 Further out in the Future! Controlled allocation of Nitrogen gives Less phytoftera Less alternaria Farmers understanding their part of the responsibility for disease problems Crop rotation Diversity in choice of varieties Diversity in choice of chemicals New varieties with better resistance against phytoftera A lot of new varieties will appear in the coming years How to control resistant break down?? Alternaria Decision support system??