This post is a text digest of the new Scaffolds Podcast. To listen to the original, visit the following link: Scaffolds Podcast  

Entomology Update with Monique Rivera 

Most of the state is still at silvertip and there is still time to get an early season oil applied. Three more reasons to consider applying this early season oil would be: 

• Number one, if you previously have had infestations of San Jose scale or woolly apple aphid. This specifically targets them in the sensitive time before they establish for the season.  
• Secondly, oil generally targets all pests that may have been overwintering in crevices of the tree. As broad spectrum products are continually removed from the toolbox, oil will continue to be an important tool in the general management of insect pests.  
• Lastly, mite and scale population trends are typically not the same each year, and weather conditions are certainly among the most variable of factors in the pest scenario from one year to the next. And therefore consistently applying an early season or dormant oil will help to manage that variability across the season.  

If you’re interested in implementing mating disruption for the various internal lepidopterans, it is time to get the pheromone dispensers and traps installed. It is ideal to do this pre-bloom. The degree days will accumulate over the course of bloom and you will be able to catch and disrupt the first generation. 

Pathology Update with Kerik Cox and Liga Astra Kalnina 

In the Hudson Valley, it looks like we have a low infection period predicted for the fifth and the 6th. Weekly maturity is about 12% and about 8% weekly spore release. The trees are just at green tip or shortly after. If a variety is not at green tip, it’s only going to be a degree day or two away. If you have copper and you’re using it a green tip, you’re probably still safe to protect that new tissue from primary infection, and we’ll get rid of some of that inoculum from both apple scab and fire blight. That low risk period is coming up with about 8% ascospore release. It’s not a heavy ascospore release, it’s going to be a light infection period for the most part. But if you haven’t made a protectant application after the 31st, probably it would have been good to get one on by the fourth or before any coming rains for the rest of the week.   

The Capital Region and Champlain Valley are not quite at green tip yet, but you could have green tip on some of your cultivars. Even if so, the maturity is going to be so low and the weekly release is going to be so low that you really won’t need to make a lot of applications for them. If you haven’t done your spring urea or your silver tip applications, get one of those on at your earliest convenience before the rain events, or if it’s already raining, just make one a little bit after and get yourself nice and prepared. Drop that fire blight and overwintering scab inoculum in those buds so that when Green Tip comes next week, you’re all ready for it.  

And so with that, I want to talk a little bit about Green Tip to bloom management. At green tip it’s going to be advisable to start looking at fungicides for Apple Scab and time these to infection events that are predicted by the weather conditions for any application. It’s advisable to use a forecasting system such as NEWA or RimPro, or whatever you like to use, or even just your weather app. Some of our new research that Liga has been doing suggests that you can do pretty well just watching the weather on your phone. Anyway, the weather app won’t identify ascospore releases and the potential infection events. You can use one of the models for those, but it’s the best way to get the best bang for your fungicide investments. And so regardless of what Apple scab forecast simulation you’re using, you really want to put your fungicides on for the biggest releases, those greater than 15% to 20% discharges. You can use lighter materials during the other periods, but look for those weather conditions that are going be 15% to 20% ascospore discharge and really target those.  

So as we start getting into the half inch green period, it’s going to be time to cease those high metallic copper equivalent copper applications. You can probably get away with it into green tip but as you start moving deep into half inch green, you’re going to want to pick a different protectant program and one of the more popular ones is the Captan-mancozeb combination. You take the low rate of each and you mix them together. We call it “Captozeb” and it gives you excellent residual from the mancozeb and all the redistribution properties of Captan. It’s not going to have post infection activity. So get it on before those big discharge events. If we get more than one and a half inches of rain or one inch of rain within the next seven days, you might want to put it on again.  

 As you’re moving towards bloom, or if we have a lot of rain days in a row, it might be time to use one of the single site fungicide products, such as the Cevya or Luna Tranquility, Luna, Sensation, Flint, Fontelis, or Merivon. Syllit is a good option at this time, and I’ll talk about that briefly. Rally and Rhyme are two additional options. If you have powdery mildew, Inspire Super. If you’re more heavy on the scab susceptible cultivars, Miravis and Aprovia are all excellent products that one could use. As you get closer to Bloom, they’re going to have activity against powdery mildew, apple blotch, other fruit rots as well. Some of these things as we start to approach bloom could cause a few latent infections. The captozeb is not going to be as strong against these.  

At the same time, when you are going forward with your single sites, you don’t want to apply them solely for post infection activity. Instead, think about making the application between periods, focusing on protecting against the period with the biggest discharge, but maybe giving yourself a little bit of bonus kickback against the one that just happened. So you can look at situations where there’s a big ascospore release forecast, like one that’s 15% or higher. What you end up doing if you get one of these scenarios, you take your single site fungicide and you apply it include about 3 pounds of mancozeb. And you’re going to see we just had a little bit of rain, and you see the forecasting period coming in the distance with a 15 or percent more, apply it about 24 to 48 hours after that last little insignificant infection period and give yourself about two to three days before the big one. In that scenario, the application will protect against the one coming forward and maybe give you a little bit of curative activity if anything slipped forward in the previous week.  

 One of the best materials to use for this is Dodine or Syllit. Now, we lost it in the 1970s and it slowly became that our populations were selected for resistance to other materials and dodine resistance has almost effectively disappeared from New York State. This is an excellent material to use, but you can only use it twice before pink. So if you do have a big infection, and you’re allowed to use dodine on Long Island, that will be the time to give that a shot. Off the top of my head, I can’t remember if Syllit is allowed on Long Island, but it has a lot of other restrictions on it.  

 Other good options to use would be the Aprovia in these type of scenarios, the Miravis, Luna Tranquility, Cevya, or Inspire super, particularly if you’re worried about scab, those are some good ones. As we get into like bloom and partially into bloom, the single site fungicides that have QoI’s or Strobilurins like Luna Sensation or Merivon are going to be really good because they’re still much more effective against mildew, and they’re going to be better choices in that area.  

And once you start hit bloom, you can begin to think about mildew as well as dealing with apple scab and a bunch of these other things. So Strobilurin or QOI fungicides can really help clean up that mildew as well as do a good bit of your scab, particularly those premixes like Luna Sensation, Merivon type products as well.  

State of the State with Anna Wallis 

Each week I’ll be providing a roundup of the degree day accumulations and phenology from the major production regions of the state. As always, this information I’ll be sharing has been aggregated from regional specialists including Mike Basedow, Janet Van Zoeren, Mario Miranda Sazo and Dan Donahue. It also includes my own observations and information collected from NEWA.  

To start? What are degree days and what do they mean? In case you haven’t been calculating degree days lately, or if you’re new to the game, here’s a quick reminder: degree days are an indicator of heat accumulation, and they’re used to estimate pest activity and plant phenology. As it warms up, things move and grow more. They can be calculated using different base temperatures, which just means that we start counting the heat accumulation only if we’re above certain temperatures. Base 43, 50 and 55 Fahrenheit are all common base temperatures for early phenology and past predictions.  

For example, the green tip predictions that we’ll be talking about today have been used historically. Base 43 Fahrenheit is used, so we only count heat units. If temperature is above 43, it can be calculated on a daily basis using daily average temperatures, or it can be calculated more precisely by creating a curve, such as the Baskerville Ermine method or “BE”. The good news is, you don’t have to calculate them. You can find the degree day accumulations on the NEWA website for many of the locations throughout the state. Equipped with a physical weather station, the Degree Day Calculator tool includes the accumulated degree days and the five day forecast. If you’re unable to find a nearby station, you can instead use the Degree Day Calculator that’s been created by the Climate Smart Farming Tool, which is a partner program at Cornell University. This tool calculates degree days using estimated temperature data. All of this information is on the NEWA website.  

So the early season phenology predictions are in. Each part of the state has been making predictions for green Tip. They appear to be a day or two sooner than predictions made earlier this year, but still we’re averaging a little bit later than last year. Usually, green tip occurs after approximately 99 to 144 degree days Base 43 Fahrenheit have accumulated since the beginning of the year. This is based on historical averages from McIntosh, which tends to be a couple of days earlier than some of our other major varieties, like Gala, Honeycrisp, and Fuji in the Hudson Valley, which is the earliest along.  

Trees are at approximately 50% silver tip, 50% green tip, with considerable variability between locations, blocks and varieties. As we can expect, this is about five days behind normal in the Lake Ontario region, green tip is expected as early as April 11 or 12th for early varieties near the lakeshore and April 14 or 15th for later varieties. Sites farther inland are expected to be a couple of days behind.  

In Saratoga County, some of the orchards are reporting silver tip now, and green Tip is expected in the next week, and that’s fairly close to average. In the Champlain Valley, trees are mostly dormant still, although a couple of silver tips can be found in earlier varieties, the cooler weather we’re expecting for the next few days can keep things that way a little bit longer. 

The degree day accumulations across the state as of the end of the day on Tuesday, April 4, are Geneva, 77 Highland, 176 Clifton Park 81 Peru, 29 Waterport, 50 Williamson, 63.