By Darren Hefty

Is this another mild winter?  Will there be a heavy onset of stripe rust in the south early this spring that blows up?  These are questions that can’t be answered yet, but they involve situations you must pay attention to if you’re a wheat farmer.  Stripe rust severity cannot be accurately predicted this early, but you can certainly be prepared to protect your crop.  Here are a few ideas to make you money and allow you to sleep comfortably at night.

First of all, stripe rust is a fungal disease.  The key word there is FUNGAL.  There are a number of bacterial disease problems hitting various crops that you don’t have good treatment options for.  However, fungal diseases can be stopped for the most part by using preventative fungicide applications.  Which fungicides work best on stripe rust depends on the stage of crop growth.

Second, scouting is over-rated.  Don’t get me wrong.  I’d recommend scouting every field you have every week of the growing season.  However, the fungicides we have today work so much better when they’re applied before disease is in your field.  Once there is enough disease to actually see visual symptoms, you’re already too late for the fungicides to work their best; and you’re too late to save every bushel of your yield potential.  You have to spray before disease is there to do the best job.  That’s why I say scouting is over-rated when it comes to stripe rust.  So what can you do?  Here’s how we see stripe rust management throughout the growing season.

EARLY SEASON – Herbicide Timing

If stripe rust overwinters in your area or if you are one of the first to have stripe rust spread into your fields, chances are you’ll be spraying for this disease right about the time you’re spraying for grass or broadleaf weeds that are beginning to populate your field.  Straight strobilurin family products are the usual choice here, but you could choose something less expensive, too.

  1. Headline – often used at a half rate to save money at this stage.  For what your wheat is worth, it’s much easier to justify using a full rate these days.  The logic behind using a half rate is that you only have a very small wheat plant to protect and the protection will only last for a couple weeks on the plant parts the spray covers.  Since you’ll be coming back soon with another fungicide, why spend the extra money?  The downside of the half rates is you are increasing your risk for diseases to become resistant to that particular fungicide.  In fact, we’re already seeing Frog Eye Leaf Spot resistant to strobilurins like Headline in some southern states.
  2. Evito – a strobilurin similar to Headline.
  3. Quadris – the original strobilurin used in many crops.  Still an excellent product.
  4. Tilt – a triazole fungicide.  It’s very inexpensive.  Half rate or full rate? See the discussion on Headline, but when it only costs an extra $2 to run with the full rate, especially considering Tilt is weaker than the other products, I’d invest the $2 and run with the full rate every time I spray Tilt or one of its generic competitors.

You could certainly use something like Quilt or Stratego, as well.  In fact, they will likely work as good or slightly better than the 4 options listed above.  If you knew for sure you would not be making an application at flag leaf timing, then a combo product would be my choice.

FLAG LEAF

The flag leaf is the most important leaf to protect because it contributes the most towards feeding and supporting the grain.  Flag leaf is also the normal timing where we see stripe rust spread into the Upper Midwest.  Here’s where we really like to see the combination fungicides used, although you could still use a straight strobilurin product, too.  All three of these combination herbicides are very good:

  1. Stratego – Gem (strobilurin) + Tilt (triazole)
  2. Quilt – Quadris (strobilurin) + Tilt (triazole)
  3. TwinLine – Headline (strobilurin) + Caramba (triazole)

HEADING

If stripe rust happens to hit right at heading, you have three alternatives that will protect you from head scab (if properly timed), stripe rust, and other diseases.

  1. Prosaro – This is significantly better at head scab protection than Orius or Folicur.  If you know you’re going to have a disease issue or suspect there will be one, it’s easily worth the investment.
  2. Caramba – This is also much better than Orius or Folicur at head scab protection.  Depending on the trial you look at, Caramba and Prosaro are generally neck and neck at the top of the comparisons.
  3. Orius (generic Folicur) – Choosing this option is a much lower investment than the first two products discussed.  If disease pressure, especially from head scab, is very high, you would have been happier with the first two choices, but this one is not bad.  Orius has a decent level of disease protection and is the top choice for farmers who either don’t expect to see much disease or don’t want to invest more than just a couple bucks per acre.  Since the price for the full rate is only about $2 an acre, though, the odds of getting a payback on this investment are nearly 100%.

SUMMARY

Stripe rust is a horrible disease that can rob a significant amount of your yield – 10 or 20 bushels in some cases.  If stripe rust strikes early, the yield impact can be even worse.  Don’t worry, though, because there are many products you can easily apply yourself to stop stripe rust before it ever gets started in your fields.