Combatting brown rot


#1

Hi all,

I’ve struggled with brown rot on stone fruit the last few years. I’m hoping the more experienced here may have some suggestions as to how to deal with it. I know of the importance of orchard sanitation, but besides that what can the homeowner do? Any sprays that work well and are not prohibitively expensive? And what sort of spray program should one follow? I’m happy to use synthetic sprays if they work. Do very late stone fruit manage to avoid brown lot better than earlier ones? Thanks for any help you can provide. I’m in suburban MD, as you can see on the great map speedster1 put up.


#2

Hi Neil, we are in a similar location and I have had the same problem. Here is my review of the key preventatives.

  • Orchard sanitation: if you see any fruit with any rot at all, get it out NOW! If its bad rot weather you may need to be looking frequently.
  • Pruning open: on all my peaches and plums I prune back to scaffolds over the winter - stub all the long shoots down to 4" or so unless you want to expand the tree scaffolds. Also the number of scaffolds should not be too many. Additionally, in summer prune off 1-2’ from the tall shoots on top that may be blocking the light from the fruit (keep the leaves that are a foot or so from the fruit, prune out further away ones). Fruits that are getting good sun are much less likely to rot.
  • Sprays. I used sulphur and Serenade for years, putting one or the other in every spring spray and then doing several over the summer. While I got OK results, I switched to synthetics a few years ago. Monterey Fungi-Fighter (propiconazole) is easy to get and works pretty well. For next year I am using Indar which is supposedly even better, but you need to buy a large amount (note I bought a gallon and will sell a pint of it to you if interested, PM me if so). You need to spray in the summer period two weeks or so before ripening. I found MFF works pretty well but I probably did not do enough sprays. More sprays are needed in rainy periods compared to dry periods - July is usually the worst for us as August is often dry. But every year is different - watch the weather and watch the fruits for rots to determine when to spray.

#3

I use 2 products Monterrey Fungi Fighter, and Bonide’s Plant and Tree Guard. Both contain fungicides to battle brown rot. They have different modes of action, and attack in different ways, so it’s a two pronged attack on Brown Rot. Follow label directions. You have to use a sticker too, Nu Film 17 is a good one. The Bonide product has insecticide too. I also spray with copper before they break dormancy and also in the fall. It helps eliminate overwintering fungi on trees, and helps against peach leaf curl too. I sometimes use lime-sulfur in the fall instead of copper. My stone fruit has been coming out great.
Scott’s suggestions I do too.


#4

Scott,
What is your recommended rate per gallon for Indar?


#5

Scott, I don’t have enough trees to justify a pint of Indar, otherwise I’d be happy to go in on it. I’ll get some Montery Fungus Fighter and aso try some copper spray before dormancy is broken. I also plan to do some serious pruning of trees that have become far too large, which shoud help remove some sources of infection. It is very hard to keep up with the growth rate of peaches!

Any thoughts on the issue of brown rot and late peaches, stone fruit in general? If that helps, I’m thinking of grafting over some trees to late varieties (also might help with squirrels – three years ago I did have a great crop of peaches - no rot - but the squirrels stripped the tree. I find that after about mid-September they are not nearly as interested in sweet fruit, but turn to nuts.)


#6

Yes, the later, the more chances to get it. Early peaches are the best. So it you’re getting it on early peaches, your orchard is infested with it no doubt!


#7

We have a wiki page for that – http://growingfruit.org/t/spray-amounts-wiki

It looks like 1.5 tsp/gal.

@Austransplant, MFF should be pretty good. I have some I am not using that is yours for the taking if you are ever up here.

I agree later is worse generally. But it peaks sometime in August, after that things don’t get any worse. For European plums the really late ones end up being several notches better in fact - Middleburg and Golden Transparent Gage are my most reliably cropping (and not rotting) Euro plums.


#8

I have and have used MFF for five or six years and it is excellent for where I live. I have just changed to Indar as I have increased the number of stone fruit I grow by 50% and rot has become more prevalent.


#9

That cannot be right when Cornell calls for 6oz Indar per acre per app. That usually comes to about 2.5 Oz per 100 gallons or 5 TBS, but lets call it 6. That’s only 18 teaspoons per 100 gallons. Cheat up and it’s a quarter tsp per gallon. A Gallon of the fungicide should take a while to use in a gallon sprayer.

What I have found to be most important is the month leading up to ripeness. I usually get protection with peaches with a single application of Indar a month before ripeness, with nectarines I do a second spray 2 weeks before.

I’m protecting a lot of stone fruit at a lot of sites but we are generally not as humid in S. NY as in Maryland. However, I manage to succeed with this low number of apps even on very humid seasons and have for a couple of decades now.

Now pristine fruit is another matter and peach scab can get started early.


#10

Oops! The 1.5tsp I thought I got from you. Will fix the wiki to 1/4tsp per gallon. What you have from Cornell is conformed by the label.


#11

Not unless it was an evening submission. Don’t trust me after I’ve had my evening bottle of ale. I’m a very cheap date when it comes to alcohol.


#12

I am trying a product called Rally (Myclobutanil) this year. All I know about it is that it was highly recommended and expensive but it can be used on many fruit trees including my wife’s roses.


#13

Unfortunately myclobutanil is not very effective against BR. Rally is expensive because you bought a life time supply (enough for 400 gallons, at least). Most here purchase it as Immunox- the brand name of its form in a home orchard quantity.

It’s label may still list BR as one of its targets but commercial growers no longer use it for that purpose because it just doesn’t work well. Indar is in the same class of chemicals as is Orbit, which is packaged for the home grower as Monterey Fungus Fighter. These two are much more effective.

Myclobutanil works extremely well against non-resistant apple scab and cedar apple rust.


#14

Alan,
I had the experience of what you typed there and know that’s a true statement. Immunox had little effect against brown rot in my experience.


#15

I don’t envy anyone trying to measure it to make a gallon of spray. The label calls for shaking the mixture before measuring and this makes it extremely foamy. I need to compare the weight per volume of the foamed up stuff to the straight liquid because I wind up hedging my bet by using much more of it.


#16

The biggest factor in brown rot is rain/dew/humidity. I know this is obvious, but it has some practical application for areas other than CA.

In the lower Midwest, the driest part of the year is generally toward the end of July/first part of Aug. Generally not much rain, humidity or dew. I find peach varieties ripening about that time almost never get much rot.

When it gets to about mid/late Aug. there starts to be a lot of dew on the fruit in the mornings which promotes rot.

Early in the season is our most rainy weather and can be very problematic for controlling rot.

Of course there is a lot of varietal variance when it comes to rot resistance. I think Bob posted a chart of varietal resistance to brown rot fairly recently.

Scott’s cultural recommendations and harvest window/varietal picks are important for managing this disease. Nevertheless (I hate to say it) an adequate spray program, like those discussed in this thread, is the strongest tool for BR prevention.


#17

What peach do you grow that ripens in that window?


#18

My biggest problem here is bacterial spot, I had it the first year. Last year I didn’t see any, the spray program worked. I’m about to spray copper as soon as the day is above 40F. I’ll spray a 2nd time too. I like to put down 2 sprays of copper while dormant. In the fall I used lime-sulfur as stated. So no copper sprayed yet. I will have to eliminate the lime-sulfur, as it is not available anymore. I still have a few years of stored product though. I believe that changing sprays up, and all keep the pests guessing what’s coming. Also one product may be more effective than another. I use other fungicides for tomatoes, strawberries, etc. and often will hit my trees with it too. Like Captan, and Chlorothalonil. I have a problem with gray mold on strawberries and Captan works well if in acidic or neutral water. I spray before flowers open. Stop once they open.
Captan prevents scab and twig blight from brown rot. Works well on cherries
Chlorothalonil. also fights scab and brown rot blossom blight, shothole, Cherry leaf spot.
I probably would not use these on trees, but I need them for tomatoes and strawberries, also other fruit, so any extra goes on trees. Easy with Captan as the strawberries require a super dose, so for trees I have to dilute it down again. It fills the spray tank again for the trees.


#19

Derby,

In our area, there would be quite a few. Pretty much anything ripening around Ernies Choice (+11) to about Loring (+20) would be ideal for our area for avoiding brown rot most years.

John Boy II, PF 17, Winblo, Harrow Beauty, Allstar, Glohaven, Contender are a few I grow. One could go outside that window and still be fairly safe most years (down to about +7, or up to about +25).

I agree w/ Drew that bac. spot is a bigger issue for me than rot (but it might not be if I didn’t spray for rot). The problem w/ bac. spot is that it takes a lot more sprays to protect the fruit and antibiotics are expensive. I am trying to remove varieties prone to spot.

On the bright side, bac. spot doesn’t render the fruit unusable, like rot, but bac. spot can cause excessive leaf loss, which weakens the tree.


#20

Thanks, lots of information there. I am glad to see contender there on your list. I plan on grafting some this spring.