I returned very tired from my conference in Spain with a realization I that I needed to get into the orchard to get a scab spray on, as it had been ten days since I treated the orchard when we were just at green tip. Needless to say, we are in full scab management season with ascospore maturity creeping up, and significant wetting, especially like we saw today, that can discharge a lot of spores. Hours required for infection to occur are relatively low with the temperatures in the 50s that we are seeing this week. Fungicide coverage should be maintained during this wet week, and a material with kick-back activity (FRAC codes 3, 7, 9, 11- be sure to rotate among these!) applied should you have any question on coverage of protectant fungicides. Use of these materials should help with management of other diseases, including powdery mildew and cedar apple rust, as well.
For the time being, I’m pretty confident that we can consider fire blight a non-issue heading into bloom. That can change quickly should things warm up. Insect management should be on your mind, though. This is also a good time to get your first soil-applied nitrogen fertilizer down. In many cases, split applications are more useful than a single application, timed at tight cluster to pink and a second application at petal fall. Without a foliar analysis (which is always the gold standard for developing fertilizer recommendations), growers should err on applying a total of 30-40 pounds of actual nitrogen per acre whether in one or two applications.
Many growers know that I am generally not in favor of insecticide sprays at pink unless scouting indicates a need because of the residues that would be present for pollinators to be exposed to at bloom. But this is a great time to be monitoring pest populations to be prepared to manage them when the time comes. These comments are from my graduate student Eli Wilson, who is implementing a scouting program with a subset of growers:
We’ve entered May and while I am sure apple scab is on your mind it is also time to start thinking about putting your dog wood borer traps out.
Also, if you have not yet set out your sticky card traps or recorded your scouting data for Tarnish Plant bug then please do!
Here is what you need to know about the dogwood borer (DWB):
The adult form of the dogwood borer is a small, clearwing moth that is shown in the image below. They have approximately a 1-inch wingspan and have a black and yellow color pattern making them resemble wasp. They have mostly clear wings with circular windows at the tips. The larvae of the dogwood borer (DWB) are about ½ inch long and can range from white to light pink with a large brown head.
This is the time of year that the adult dogwood borers begin laying their eggs in the crevices of tree bark, so it is important to be monitoring for their presence in your orchard.
The dogwood borer larvae are the ones that cause the damage, feeding on the phloem and cambium layers of the tree. Signs of an infestation may first appear as a pile brownish red frass on the outside of an entry hole in the tree trunk. While a few borers will not cause significant damage a population can build over the years and lead to reduce tree vigor and even girdling. An image of the larval form of the dogwood borer (DWB) is also shown below.
You will be using two of the six orange TRÉCÉ PHEROCON VI DELTA TRAPs to monitor the dogwood borer in conjunction with one of the provided lures that are labeled “DWB”.
The lures should be replaced every 4 weeks and you can replace the stick liners every week if you choose. If you do not replace the liners each week, be sure to remove all the trapped dogwood borers after recording that week’s catch total.
The orange Delta Traps should be hung within the tree canopy at approximately 4-feet off the ground as shown in this instructional video: Hanging Delta Traps
I hope this information is helpful, if you have any questions, comments, or concerns please feel free to reach out!