By Brian Hefty
Fungicide and insecticide applied at heading could add several bushels to your crop this year under the right conditions, but is it worth spraying?
FUNGICIDE: The most important thing you need to know about applying fungicide at heading is which products NOT to use. Strobilurin fungicides should never be applied at any wheat growth stage past flag leaf, or the odds of DON levels in wheat go up dramatically. The products we encourage you to use at heading are Prosaro, Caramba, and Orius (generic Folicur). They are all in the triazole family of fungicides.
Orius is excellent on rust, including stripe rust, but is only marginal on head scab (fusarium head blight). The great thing about Orius is while it used to cost $15 an acre for Folicur (the name brand version), Orius now runs $2 an acre for the full 4 oz use rate. If you are considering skipping the fungicide at heading, I would suggest you at least consider Orius, as $2 an acre is a small investment.
Prosaro from Bayer is a combination of Proline and Folicur. Prosaro is similar in control of rust to Orius, but is far superior on head scab. The use rate is 6.5 oz to 8.2 oz, depending on your need for residual and the potential severity of the problem. Same thing with Caramba and its rate range of 13.5 oz to 17 oz. Caramba from BASF is a straight product that is comparable to Prosaro. Both products will cost $13 to $18 per acre, but rebates from each company could lower your net costs slightly.
Is it worth it to spray for disease? The problem with fungicide applications is they must be applied before disease sets in. You can’t scout, identify the problem, and then spray while still maximizing yield. That’s why it is always more hit and miss with fungicides compared to insecticide and herbicide treatments. However, the ratio of the cost of treatment to the wheat price is pretty good right now, making your odds better than normal to get a good ROI. Keep in mind, too, that diseases need 3 things before they can ravage your crops: a host, a favorable environment, and the presence of the disease. If you are planting relatively susceptible varieties and conditions turn wetter and/or more humid, you’ve got far greater risk and far greater chance for a good ROI with a fungicide than if you are planting relatively tolerant varieties in a drought year.
Timing is key. If you decide to treat for scab, rust, and other diseases at heading, our recommendation is to spray when you are at 10% to 15% flowering. I know this is a small window, but it’s traditionally when we’ve seen the most yield response.
INSECTICIDE: Insecticide applications in wheat are rapidly growing for 3 main reasons: the value of the crop (between yield and price) is worth much more than normal, the cost of insecticides has dropped to record low levels (most cost $2 an acre for the full rate), and there seem to be more bugs present each year.
Certainly, if you have very low levels of harmful insects, we discourage spraying an insecticide. Scout your fields prior to spraying, and if you are finding insects like aphids, grasshoppers, or certain flies that could cause a problem at any point during the season, spray. The pyrethroids, like Silencer and Declare, are highly effective on most wheat insects and can be mixed with almost any fungicide or herbicide product you use. More care must be used when applying Lorsban, as that product can add more leaf burn than the pyrethroids. However, Lorsban is definitely better on mites than Silencer and Declare, if mites are present.
While it may be a tough choice to spray or not spray in your area, there are fortunately some very inexpensive alternatives that may make your decision easier. Again, the full rate of Orius is just $2 an acre, and an additional $2 worth of Silencer or Declare will wipe out most bugs. If you want better scab control, switch from Orius to Caramba or Prosaro.