Knowledgebase

Apple fungus? #753115

Asked May 31, 2021, 5:19 PM EDT

Hi there, I have one Honey Crisp and one MacIntosh apple tree spaced about 10-12’ apart. I’ve had numerous pests over the years, but seem to have some kind of fungus on both, most noticeable on the Mac. What is the best product to manage this now, and in the fall? I only had a few blossoms this year (bumper harvest last year); will this fungus affect my apples?

Chittenden County Vermont

Expert Response

Trying to grow apples in the backyard and keep them disease-free is difficult without a lot of spraying. Most commercial growers have already applied 4-5 fungicides by now starting at green tip and then weekly through the end of June. They will often spray 10-15 times/season. Macs and Honeycrisp are both susceptible to apple scab, the most common fungus disease. This is the one that growers direct most sprays to. And yes, the fungus disease will infect your fruit.
Are you trying to stay organic? This is more difficult because of the limited materials (copper and sulfur, mainly).
This is an excellent publication geared mainly for organic commercial growers but it has great info on fertility, pruning, and controlling insects and diseases. Through pruning is important to allow light and air to circulate around the tree, as this minimizes fungal diseases.
https://ecommons.cornell.edu/bitstream/handle/1813/42886/organic-apples-NYSIPM.pdf?sequence=1

and another for home gardeners: https://extension.umn.edu/fruit/growing-apples#diseases-1143611

The easiest thing may be to purchase a home garden fruit spray that contains both fungicides for apple scab and insect control.
Here is the main fungus disease you will be battling.

https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/diseases/scabs/apple-scab.aspx

Trees need to have the fungicide applied BEFORE the fungus attacks, there is no curative effect of the fungicide.

Good luck!

Ann 

An Ask Extension Expert Replied June 02, 2021, 10:52 AM EDT

Thanks so much for these references.  Gardeners Supply recommended All Seasons Horticultural & Dormant Spray Oil for late fall and early spring, and Citrus Fruit & Nut Orchard Spray to use now. Also said I might have some success stabilizing this season using Revitalize. 

 

I meant to ask if it’s unusual for the fungus to travel onto my Concord grape vines? They have a similar rust appearance on many of the leaves.

 

I am not 100% organic, although I’d prefer to use as little fungicide as possible throughout the growing season. I actually sprayed with a Fruit Tree application just after blossom drop, thinking it might be an insect causing some of the damage until it became clear that it’s more of a fungus or topical disease.

 

Thanks again,

Lori

 

From: Ask Extension <<personal data hidden>>
Sent: Wednesday, June 2, 2021 10:53 AM
To: Lori Roberts <<personal data hidden>>
Cc: Ann Hazelrigg <<personal data hidden>>
Subject: Re: Apple fungus? (#0023046)

 

The Question Asker Replied June 09, 2021, 11:49 AM EDT
Received From: Ann Hazelrigg <<personal data hidden>>



No, fungi that cause apple diseases will not affect grapes. They have a whole other set of their own fungal diseases! That being said, the conditions that are conducive for fungal diseases (wet cool weather) will increase these diseases in apples and grapes.

 

I am not sure what is in citrus nut and fruit spray but it is likely a combination of insecticides and fungicides. You need to follow label directions to cover all the bases. It will involve sprays from green tip (just as the leaves are coming out) through June I imagine.

 

Ann

 

From: Lori Roberts <<personal data hidden>>
Sent: Wednesday, June 9, 2021 11:44 AM
To: Ask Extension <<personal data hidden>>
Cc: Ann Hazelrigg <<personal data hidden>>
Subject: RE: Apple fungus? (#0023046)

 

Thanks so much for these references.  Gardeners Supply recommended All Seasons Horticultural & Dormant Spray Oil for late fall and early spring, and Citrus Fruit & Nut Orchard Spray to use now. Also said I might have some success stabilizing this season using Revitalize. 

 

I meant to ask if it’s unusual for the fungus to travel onto my Concord grape vines? They have a similar rust appearance on many of the leaves.

 

I am not 100% organic, although I’d prefer to use as little fungicide as possible throughout the growing season. I actually sprayed with a Fruit Tree application just after blossom drop, thinking it might be an insect causing some of the damage until it became clear that it’s more of a fungus or topical disease.

 

Thanks again,

Lori

 

From: Ask Extension <<personal data hidden>>
Sent: Wednesday, June 2, 2021 10:53 AM
To: Lori Roberts <<personal data hidden>>
Cc: Ann Hazelrigg <<personal data hidden>>
Subject: Re: Apple fungus? (#0023046)

 

The Question Asker Replied June 10, 2021, 9:03 AM EDT

No, fungi that cause apple diseases will not affect grapes. They have a whole other set of their own fungal diseases! That being said, the conditions that are conducive for fungal diseases (wet cool weather) will increase these diseases in apples and grapes.

I am not sure what is in citrus nut and fruit spray but it is likely a combination of insecticides and fungicides. You need to follow label directions to cover all the bases. It will involve sprays from green tip (just as the leaves are coming out) through June I imagine.

Ann

An Ask Extension Expert Replied June 11, 2021, 9:05 AM EDT

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