Using Captan on Apple trees

Does this replace using Immunox alltogether?

Sort of. Captan doesn’t have good efficacy against Cedar Apple Rust and although it is effective on powdery and downy mildew it somewhat lacks in that area. For pretty much everything else (especially in apples) it is pretty much the ultimate fungicide, especially when cost is considered. If you look at a comparative efficacy chart online you’ll see what I mean.
Captan is often combined with sulfur to achieve better mildew protection and for resistance avoidance. Captan spray guides mention this combo and when combined each is sprayed at a lower rate. Those two fungicides are, by far, the cheapest ones out there. Jonathan, Macs, and maybe Red Delicious can be harmed by the combo under the right conditions. Captan alone has no warnings for any apples that I am aware of.
Best to spray the Immunox (myclobutanil) when CAR is on the prowl or on susceptible varieties and go with Captan otherwise. You are limited to 3 sprays max per season with Myclo and I think 6 with Captan.


Can it be mixed together with Immunox and triazicide

It absolutely can.

I agree Captan can be mixed with immunox and triazicide. Thanks for bringing up the topic John.

Most of the time fungicide tank mixes are used commercially to avoid resistance management. Manufacturers have even started licensing premixes like Luna Sensation to avoid resistance.

However, for a small number of trees, building resistance isn’t something to be too worried about.

Numerically speaking, the disease population of, say, a backyard orchard is small enough that developing resistance is unlikely.

If you think of it this way, a 10,000 square foot back yard orchard may have 100 trees. A 100 acre apple orchard would have at least 50,000 trees. The commercial orchard would have proportionately more leaves and proportionately more scab fungi. For the commercial grower, since there are so many more scab fungi spores, there is a much greater chance one of the fungi will mutate to become immune to the the scab fungicide being used.

Perhaps an analogy would be a boy standing on a wooden bridge tossing a baseball in the air and catching it. If he’s a good ball player he could throw it 10 times in the air and catch it every time. He might even be able to catch it 100 times in a row. But if it throws it in the air 1000 times he may miss once and his ball will bounce off the bridge and land in the water. A commercial grower repeatedly using one fungicide is likely to have his ball land in the water.

Appleseed makes a good point about the cost of Captan. It is relatively inexpensive compared to other fungicides and is effective against scab. There are cheaper fungicides which are very effective (like Indar) but those aren’t typically packaged in quantities for backyard orchards (i.e. one gal. of Indar will treat 16 acres).

Captan is a “multi-site” fungicide on scab, so the probability of scab mutating to form resistance to Captan is very unlikely. I don’t know much about powdery mildew. It doesn’t affect apples in my region much.

We have CAR sporulating here right now. My neighbors large cedar trees have so many fruiting CAR galls, it looks like it’s decorated with Christmas ornaments.

Thanks for the replies, I will add this to my spray program.

Indar is cheaper than Captan? Does it have similar wide spectrum efficacy like Captan? I thought I had compared them all at least a 1000 times and Captan was the runaway winner every time.
I do not remember ever reading about indar though? There must be something keeping it out of the multi-purpose sprays like Bonide’s etc…they all use Captan I think.
I’ll have to look into this as I’m all about cheap. lol :smiley:


Indar is a little cheaper. Looking at a 2014 catalog from Midwest Grower Supply (don’t have a 2015 catalog) a 30# bag of Captan 80 is $123.50. One gal. of Indar 2F is $295.

On apples the max rate of Captan is 5 lbs./acre at a cost of $20.58. The max rate of Indar (for apples) is 8 oz. acre at a cost of $18.43. Only a couple dollars difference.

For peaches, the max rate of Captan is still 5 lbs. but the max rate of Indar is 6 ounces at a cost of $13.82/acre (about two thirds the cost of Captan).

Indar used to be even cheaper when it was just labeled for stone fruits, but the manufacturer sought and received a label for apples some years back. When it was first used in apple orchards, it had “curative” activity for scab, which made it very valuable to apple growers. I suppose that and the cost of the expanded labeling made the cost of Indar increase significantly.

No Indar no longer has the curative value for scab in apple orchards because of resistance issues. I believe it’s still used extensively, but just not as effective. Indar is classified as a SI or DMI and has only “single site” activity on the fungus, which makes it more subject to resistance buildup.

I remember when Indar was first allowed to be used on apples, all the fruit specialists in the newsletters were warning about the potential for resistance of Indar on scab. Sure enough it didn’t take very long before they were reporting some loss of effectiveness of Indar because of resistance.

yeah…I read up on it last night. Didn’t check the price though. This resistance issue is apparently so bad that they are now recommending combining Indar with Captan 80 or other “contact” fungicides. Actually that 30 lb. bag of Captan is a darn good price for Captan 80, I just paid $51 ( incl. shipping) for a 6.25 lb. bag from KPS. I’d never in a million years be able to use 30 lbs. of course, but maybe their price is better on the smaller bags. I went to their site, but they ask you to request a price list. That tells me my price gets jacked up I guess.

To your point on resistance in small home orchards this may be a case where it would apply. I read where a farmer sprayed his apples that had visible scab lesions (against the recommendation not to) and sure enough, it immediately became ineffective against scab. I didn’t read all the details and maybe the resistance was already there…who knows.

I’m glad you pointed out Indar, I like learning about this stuff and no doubt you know your stuff on the subject. From my reading and our discussion though it seems to me Captan is the way to go for backyard orchardists and maybe commercial also.
I think the 28 day PHI probably kills Indar from the OTC sprays targeted to home gardeners. I think Captan is 1 day and I’ve even read about it being used the day of harvest to provide storage protection to apples etc.

Olpea…one last thing. How much water would the 6 ounces of Indar be mixed with for an acre? That you can cover an acre with 6 ounces of anything is just incredible to me. Certain things like this are just so difficult for me to get my head around…6 measly ounces. lol :grinning:

I think it’s a useful product. It actually has a zero PHI, but I use only in the early season.

It is kind of amazing. The technology has gone from older products which were measured in Lbs./acre to newer products measured out in ounces per acre. Indar used to be sold in a WSP (water soluble packet) formulation (The outer skin of the packets dissolve in water, like the little dishwasher packets of individual dishwashing powder.) The packets were only 2 ounces. For one acre, one would just toss one packet into the spray tank. Most of the agricultural pyrethroids use just a few oz/acre. I bought some Sandea herbicide this year. It uses just one ounce per acre, which kind of blows my mind. :astonished:

The gallonage per acre really doesn’t matter since the water is really only a carrier of the pesticide. The key is uniform coverage, whatever the gallonage per acre is. Some aerial spraying only uses 10 gallons/acre. I think most commercial growers use about 50 gal./acre in their orchard sprayers. My sprayer is set up to use 100 gal. acre if I drive in second gear at rated PTO speed. Oil is about the only thing which doesn’t work well with low water volume spraying. It seems to suffocate the insects better when mixed with a little more water.

Immuox is a systemic, not one that travels throughout the tree, but it penetrates the skin so it doesn’t wash off in the rain. This cuts two ways, it means a heavy rain won’t remove it the way it would Captan but it also means that light rain won’t move it to new grown tissue- this is the other reason Cornell recommends combining Captan with SI fungicides like Immunox.

Immunox also has kickback, so if the captan gets washed off and you don’t get back to spray for a couple of days it may save your butt. It also lasts longer than Captan which is why I can control scab and CAR, most sites most years, with only two SI applications.


yeah…you’re right…it’s the REI that is 24 hours.

I certainly have enough Myclo to last me for a while. I bought 6 bottles on an ebay bid for $9.99 and though it is the newer lower concentration it should last me longer than the product may be good for. My plan is to use it early at heavy concentration for CAR and then switch to Captan / Sulfur for the remainder of the season. I’ll probably combine a light mix of Daconil with the myclo in the early sprays before fruit formation.

Be sure to adjust water ph if needed when using captan, at a high ph (8 or above) the half life is only 10 minutes. Ideal ph would be 5 to 6 to prevent premature breakdown