Spraying Marion Berries

Asked September 8, 2016, 3:17 PM EDT

I mixed up a spray of Polusul sulpher spray 1 cup per gallon, which is the strongest mix recommended and was going to spray my trellised canes to get rid of blackberry mites - and perhaps some leaf spot also. However, there is so much new tender growth I am afraid I will burn it. What is your opinion? Should I dilute it to a B or C (summer) strength? Is there something better to use or should I do it at all? I really want to fight the mites that ruin the way the berries ripen, and fight the red spots that appear on the leaves, too.

Washington County Oregon

5 Responses

Please send at least 3 images:
1. an overall of the affected plants.
2. a close view of affected berries
3. a close-up of affected leaves.

I look forward to seeing your images.

"Here are requested pictures, except I cannot provide a picture of berries because season ended in June. We have trellised the new canes in August. We are having lots of new growth with tender leaves not fully emerged. That is what I am concerned about burning with the strongest solution of Polysul. My 1982 spray guide for cane berries says on page 7 "Raspberry mite (primarily blackberries). These very small (two-hundredths of an inch long) eriophyid mites are perennial pests of wild and cultivated blackberries in Oregon. The mites feed on the fruit at the bases of developing druplets. In doing so, they cause entire berries or individual drupelets to remain green and red, with a very hard character and bitter taste. ...The adult mites winter in bud scales of the canes. ...Control Lime sulfer (8 gallons to 92 gallons water) or a polysulfide compound, 10 lbs + 100 gallons water. ...Another fall spray can be applied after old canes have been removed to clean up severe infestations. ...

Because of the dilution rates you suggest -- 8 gallons to 92 gallons water or 10# per 100 gallons -- I suspect you are a commercial grower. If so, I need to refer you to an Extension Service Agent.

Please let me know.

I am not a commercial grower but a home grower, therefore the rates quoted in my old spray guide are irrelevant to me. I do not know how to convert these rates. I have mixed up Polysul spray at the strongest recommended rate (A) but am concerned that it may be too strong for the newly emerging growth. Does anyone know what I can use safely?

Thank you for clarifying your question and also adding several additional details. From what you wrote, I suspect your chemicals are as old as the outdated spray chart. If so, I suggest you recycle them via an official Hazardous Waste Collection Center or event and, then, replace them with currently available home garden products.

Newer home garden products are designed to reduce the confusion about diluting and applying pesticides safely and effectively. Different dilutions are clearly stated in home garden amounts if they can be used when plants are actively growing or dormant.

One of the challenges I have in your case is determining if the hard spots on your berries were caused by dry berry mites or the similar appearing damage from sunburn, the latter sometimes called sunscald. If I assume dry berry mites are the cause this season, then the official treatment resource from Oregon State University suggests lime sulfur spray and says this for home use: “Dormant-season spray -Spray canes in spring when vegetative buds are about 0.5 inch long. Repeat application in the fall. Some formulations are OMRI-listed for organic use.” (http://insect.pnwhandbooks.org/small-fruit/cane-fruit/cane-fruit-dryberry-mite)

A home garden material will either be a ready-to-use product or will clearly state the needed dilution. Because recent years have seen a change in which manufacturers supply home garden lime sulfur, I suggest you phone local farm stores and/or the larger garden centers to locate a retail source.