Peach Brown Rot control

Asked August 11, 2017, 5:19 PM EDT

I am a homeowner and a chemist. I have one peach tree from which I have been unable to harvest hondreds of early starting peaches because of brown rot. My best result was from use of sulfur, insecticides, sanitation and pruning, but this still had the last remaining peach also succomb to brown rot. One report said that sulfur doesn't work, another said it is less effective than Fruit tree and plant guard and Immunex. These 2 would cost me lically $70, not very economical for 1 tree. The Frac table lists products I cannot find locally. Captan has not been effective in my use. Two questions: Even though I am not a commercial farmer, Can I obtain a pesticide license so I would have access to more effective products? What should I try next?

New Castle County Delaware

5 Responses


Sorry for the delay, I didn't realize you had responded back.

Without a commercial pesticide license, you cannot purchase and apply some of the "more effective" targeted chemical fungicides. You can obtain a pesticide license by taking online training in Delaware. Please see the web page at: and certification application instructions at:

One crucial aspect of fungicide applications is timing and this year the weather made that challenging earlier in the season. One thing that may help you is some strict pruning and sanitation this fall and next spring. Removal of mummies and reduction in weeds may help to control disease and insects.

Unfortunately home fruit is challenging to produce, especially on an older tree. There are some newer resistant cultivars of peach that may be a better choice, I believe 'Venture' is one.

Thank you,

Thank You Nancy. The season is practically over. Planning for winter care and next year. I have done and am continuing what you recommended including pruning spraying and sanitation, etc, except maybe for missing some critical timing and/or more effective materials.I will check into getting a pesticide license, but costs for class and materials may not be proportionate to potential yieldsCurrently I have 2 more questions, one for an apple tree and one regarding tomato ripening while avoiding insect attack: 1.When is the critical spray time to avoid early insect attack on an apple tree? 2.Will tomatoes picked at start of reddening ripen in a plastic bag?


Apple fruit trees are much like peach and others, that they need to be on a fruit tree spray.You can use horticultural oil on apple before trees bloom in the early spring, around April 1. I think first other insect sprays should be shortly after bloom, when fruit are small.

Tomato fruit will ripen on a window sill or on the kitchen counter. Do not place them in a plastic or paper bag, and do not refrigerate.

Thanks for contacting Cooperative Extension,

Thank you,
My Apple tree problem occurs when the starting fruit is only about one quarter inch in diameter and there are still a few flowers with petals not fallen yet. These fruit get punctured by insects ( egg deposition ?) resulting in distorted , blemished and partly inedible maturing fruit, which doesn't reach the yellow delicious color of ripeness before dropping off the tree.
I don't apply insecticide spray when the few flower petals remain, to avoid killing Bees, and after the petals all fall, it's too late. Is there a better, safer way to protect these early starting fruit?
Ripening uncovered tomatoes indoors attracts bugs . I thought that the ethylene oxide given off by ripening tomatoes in a plastic bag might hasten ripening after color starts forming on the vine, thereby avoiding nature's way of enjoying the harvest before me.
Being a chemist having worked with hazardous materials makes the pesticide license acquisition a worthwhile challenge. Do you know if the application fee of $30 includes the Study materials fee of $30 or are those all extras?
Thanks again.


The best thing for early insect control on apple to help with those curculio insects horticultural oil on apple before trees bloom in the early spring. Use a 1.5% hort oil at that time. Then during bloom, you can continue to use light hort oil, maybe a 0.5 to 1.0 % but watch not to apply if temperatures are above 85 F. Neem oil may also be worth a try, or peppermint oil. another product you may want to try is kaolin clay, which is sprayed on and creates a barrier for insect probing, but washes off and is non-toxic. I am including a web site, but it's not a university or extension web site, which I usually like to recommend. Just FYI.
There is some information in the Cornell organic fruit guide, but it is a huge document!

I don't have experience with the pesticide license training, not having had one for years, but I think once you apply online the training material are included.