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  • Fungicides - V-12 App

    Nice read on a app of fungicides =- applied at V-12

    Over the years -- We have done fungicide trial's on timing of app's - This was with Kiersten Wise ( Defector to U of K ) - with a head shake ! Our finding - were about the same with no increase in yield - One time there was really no disease pressure - so went ahead and sprayed to test for any increase in yield for over all plant health = No increase in yield - Funny thing - one year that we tested - the test area's with fungicides applied , made 2 bpa lower that the non applied areas . From what I have seen - fungicides do work - when warranted - - But to just apply when thresh holds are low - it's a non event .

    Should We be Spraying Fungicides on Corn at V12?
    February 8, 2018
    ICM News
    In 2017, we tested several foliar fungicides on corn at six locations in Iowa: ISU Northwest Research and Demonstration Farm (NWRF), Sutherland; Northeast Research and Demonstration Farm (NERF), Nashua; Northern Research and Demonstration Farm (NRF), Kanawha; Southwest Research and Demonstration Farm (SWRF), Lewis; Southeast Research and Demonstration Farm (SERF), Crawfordsville; and the Ag Engineering and Agronomy (AEA) Farm, Boone. At all locations, the previous crop was soybean. Hybrids varied across locations, and were rated between 3 and 5 for gray leaf spot (GLS) resistance where 9 = most resistant.
    The purpose of these trials was to help farmers determine if foliar fungicides should be incorporated into their production. Our objectives were:
    Assess the effect of application timing of fungicides on disease.
    Evaluate the yield response of hybrid corn to foliar fungicide application.
    Discern differences, if any, between fungicide products.
    Products used and application timings tested
    In 2017, eight products were tested (Table 1). The timing of application varied by product and was suggested by the companies contributing each product. Fungicides were applied at growth stage V5, V12, R1, and V5 + R1. This was the first year we have tested applications at V12. No surfactant was included in applications made at V12.
    Effect of product and timing on GLS
    Disease severity in the lower canopy (below the ear leaf) and upper canopy (ear leaf and above was assessed around R5 (dent). The most prevalent disease in our trials was GLS, which was present at four of our six locations (Table 1). At NRF there was no GLS; and at AEA, gray leaf was present at extremely low levels.
    Table 1. Effect of Fungicides on GLS in Iowa in 2017
    There were few differences in GLS control among the products.
    Significant differences (P>0.1) were observed between times of application.
    Confirming observations from similar trials done previously, the amount of GLS observed throughout the canopy at R5 between V5 applications and the non-sprayed check did not differ.
    R1 applications significantly reduced GLS at R5 compared to the non-sprayed check.
    V12 applications were most effective at reducing GLS severity at R5. In some cases (e.g., at NERF), they were even better at reducing GLS than an application at R1.This was consistent across all four locations.
    Based on these data, should we be spraying at V12?
    I think the jury is still out on this, but I spent a lot of time thinking about why a V12 application was so effective at reducing GLS in 2017. Two factors come to mind:
    GLS always starts in the lower canopy. It is likely that the fungicide at V12 reached and protected the lower leaves of the canopy. When applications are made at R1, less product reaches the lower canopy which is obstructed by the leaves of the upper canopy.
    The V12 applications coincided with warm (80s) and very humid growing conditions (Figure 1). Warm temperatures (75-85F) and high relative humidity (>85% for several hours) favor GLS infection and disease development (Rupe et al. 1982). Consequently, I would argue that the V12 applications in our trials were perfectly timed for the 2017 season and delayed GLS development in the lower canopy, and consequently throughout the season.


    Figure 1. Maximum and average relative humidity at ISU research farms from July 1 through 30 August. 2017. Green shading indicates dates when V12 or R1 foliar fungicide were applied.

    These data suggest that an application at V12 improved GLS control for the 2017 season, which had conditions favorable for GLS development. It will be interesting to see if V12 applications are as effective at reducing GLS in future growing seasons that are likely to have different environmental conditions throughout the season.
    Also, remember there are other foliar diseases such as northern corn leaf blight or southern rust that may affect corn in Iowa. Since both of these diseases may occur anywhere in the canopy, it is possible that a V12 application may have less effect. A V12 application only protects those leaves that are present at the time of application.
    What about yield?
    No effect of product or timing was detected on yield at any location (P>0.1; (Table 2). Yields in the trials were excellent. GLS severity in the upper canopy of the non-sprayed controls was low (<10 %) at all locations, suggesting GLS in the trials was not severe enough to influence yield.
    Table 2. Effect of Fungicides on Corn Yield in Iowa in 2017
    A word of caution
    In our trials we did NOT use an NIS in our V12 applications. Adding a surfactant to fungicide applications between V12 and VT may affect ear development (Stetzel et al. 2011).
    Acknowledgements
    Thank you to the farm managers and staff at each location who managed the trial and applied the fungicides.
    References
    Rupe et al. 1982. Influence of Environment and Plant Maturity on Gray Leaf Spot of Corn Caused by Cercospora zeae-maydis. Phytopathology 72:1587-1591.
    Stetzel, N., Wise, K., Nielsen, B., and Gerber, C. 2011. Arrested ear development in hybrid corn. Purdue Extension publication, BP-85-W, 2011.

  • #2
    We need weather models to predict the rate of spread and development of GLS based on recent and forecasted temperatures and relative humidity. Because northern actually moves with moisture laden air flow that also has to be considered in weather models. Still not sure who makes the most money in this area, those who never spray fungs, those who spray every acre every year, or those who scout and spray. Too many variables including the weather in the near term weeks after spraying to believe that one of the 3 choices above has overwhelming odds of success vs the other choices at allowing a corn producer to increase net income through use of fungicides over years.
    “Democracy is the worst form of government, -------------------------------except for all the others.”

    ― Winston S. Churchill

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    • #3
      We sprayed 45 acre last year. I planned it by variety had on # from pretzel that was told responded well to fungicide. Part of the acres was riverbotttom that flooded the previous Sept before bean harvest had to work down some sand dunes didn't want to take any chances something got wash in from upstream.
      Don't get tripped by what's behind you

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      • #4
        Originally posted by flyingRoot View Post
        We sprayed 45 acre last year. I planned it by variety had on # from pretzel that was told responded well to fungicide. Part of the acres was riverbotttom that flooded the previous Sept before bean harvest had to work down some sand dunes didn't want to take any chances something got wash in from upstream.
        River basins are notorious for increased risks of fungal diseases. Fungal diseases need moisture on the leaves to grow and penetrate the leaf. Basins dry more slowly after a morning dew due to more limited air flow. To add to the risk, the river is a source of moisture that travels with air. In years with high infestations of fungal disease it is not at all rare to see higher infestations of GLS in the basin by the man made dredge ditch flowing through my home farm.
        “Democracy is the worst form of government, -------------------------------except for all the others.”

        ― Winston S. Churchill

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        • #5
          I also liked the fact it was a 96 day number that will hassle next to the river early just for bragging rights
          Don't get tripped by what's behind you

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          • #6
            Here is the approach That I have been using the past years -

            1. It starts with -- the number of corn I plant - as to disease ratings - what it's strong in and what it's not - or the most part - I use a strong disease package - and have found that there ratings are very close to what they say , I still keep a close on eye one them for disease - One other thing is that the ones that have a good disease rating - are what I call the work horse numbers - they - to me most times are not the highest yielders .

            . 2 - I still believe in scout - scout - scout ! They say - for the most part that IF you don't have disease at the ear leaf at tassel - then it's good to go - I did have one year that the corn was as clean as it could be - then in Aug . it turned HOT - Humid and Lots of rain - that pretty field -- turned into a train wreck ! I bet that that I lost at least 20 bpa - compared to others that it did not effect - But at that time - who knew ? Unless we had a model like Jabber said .

            3. Know your stuff !!!!!!!!!!!!!!!!!!!!!!!!!!!! don't depend on what your Chemical dealer or what your neighbors are saying - doing ! This comes from educating yourself on diseases - and thresh hold's - I have been to classes that ask - what percentage of disease is on a leaf ? Many would guess 50 - 60 % -- when in fact it was only 10 to 15 - remember - them specks on leafs can be deceiving , matter of fact - you can get a leaf rating chart on diseases -- as to what the percentage is -

            4. One thing I have found is How to apply if need be ???? I apply my own with a ground rig - I feel I can do a lot better job than any airplane or chopper - But there's a trade off - using the Hag - I hurt the end rows ! Then Dennis - Dan - Iowa 55 - Dave478 - Peeler - PL Dairy - DairyFarmn - Jabber - DB-51 - will call me - And then I can get off the middles and run over some that I'm not suppose to - lol -- I have never seen a study that applies crop damage when they figure the final out come of using a fungicide - lol It is always a straight row plot - trust me - them end rows count big time in the end yield .

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            • #7
              ECI question for you I've seen the coverage maps from the plane five passes that should have been 8 to cover field has any research been done on what gets missed between passes and when y9u cover whole field? I had a neighbor skip 90 ft every other passspraying aphids inbeans got good kill even where he skipped no wind.
              Don't get tripped by what's behind you

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              • #8
                Yeah Ken, I remember a few years like #2 above. One year a hail adjustor that visited one of the fields sniped "you lost a lot more from not spraying this leaf disease than the hail cost you." Yup in hindsight, he was right and as you know hindsight is 20-20- foresight when it comes to the rate of spread of leaf disease is not. He then made it sound like the decision was easy and everyone who watched their fields sprayed.

                The facts were the hybrid was rated high for resistance to GLS. The pressure was very low at tassel. The weather after pollination was ideal for spreading the disease into the upper canopy. By early August, I wished that I had sprayed every acre.

                That crop hail company never again sold insurance to me. His comment plus the fact that any time they spent in my field was clearly getting in the way of their tee time at the golf course was the kiss of death for that company at my place. If long time posters haven't noticed, I don't take criticism from smart *** know it alls very well.
                Last edited by jabber1; 02-18-2018, 07:34 AM.
                “Democracy is the worst form of government, -------------------------------except for all the others.”

                ― Winston S. Churchill

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                • #9
                  I don't take smart *** know it alls very well.

                  OR - Garage Door installers either !! LMAO

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                  • #10
                    Originally posted by ECI View Post
                    I don't take smart *** know it alls very well.

                    OR - Garage Door installers either !! LMAO
                    That would be EX- overhead door installers.
                    “Democracy is the worst form of government, -------------------------------except for all the others.”

                    ― Winston S. Churchill

                    Comment


                    • #11
                      Originally posted by flyingRoot View Post
                      ECI question for you I've seen the coverage maps from the plane five passes that should have been 8 to cover field has any research been done on what gets missed between passes and when y9u cover whole field? I had a neighbor skip 90 ft every other passspraying aphids inbeans got good kill even where he skipped no wind.
                      Not that I know of Root - Reason being - How to know where the plane missed - as in it will drift - even though you think it was missed - it still may have got a small drink .

                      I have a very friend that was a duster - retired 4 or 5 years ago - he said if they are with in 20 feet or so of there intended pass - they are doing a good job - The older planes like I worked with back in the mid 70's were Pawnee's - Ag Truck's - Ag Cat's - sprayed at ?? 110 - 120 mph - todays turbo props ?? guessing here -- 150 to 160 mph - So they will need to start there pull up's earlier to me - reverse headed back in .

                      As far as neighbor skipping 90 and got good results - that was just luck : or he really didn't have the problem as bad as he thought - skipping 90 feet would just give you them results if the aphids were that bad - another thing is , in the 90 that was skipped - was there was good bugs in them area's that did the control on the aphids

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                      • #12
                        I don't know the details might have been coffee shop fact��

                        I kinda figured the plane could play a lot looser game of horseshoe and score point than ground rig just letting curiosity kill the cat.
                        Don't get tripped by what's behind you

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