Blackberries with white druplets

I removed both Triple Crown and Apache. Both had severe druplets.

Yes indeed, there are varieties more prone to this problem. I have seen the white druplet disorder with sunny hot days after heavy rains.

Ive seen the problem in kiowas. We corrected the problem using calcium sprayings together with potassium phosphite to strengthen the fruit (cell walls). You will see the problem were more water vapor is produced, in my case berries close to the soil.

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Hi Eric

Would you mind sharing the name of the material, the rate and the timing for your sprays?

Wonder if it would be possible to mix those chemicals with a SWD spray?

I normally spray for SWD after big rains when I am unable to get the blackberries picked, so the white druplet spray would overlap well with the SWD spray.

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What does SWD stand for? Sorry, I just want to give you a proper answer.

We use to spray once weekly with a 16 liter backpack sprayer using 100 ml of potassium phosphite (there are many good brands of this one) during harvest. About three back pack sprayers in a 1200 square meter area. Usually two to three sprayings during the harvesting season. We also had some calcium on that mixture and fungicide against Peronospora sparsa (downy mildew).

The phosphorus on the potassium phosphite is not available for the plant immediately. Please do not consider it as good source of phosphorus.

The brand we use is called Cuneb Forte. However, I don´t think you are going to find that on your region. I found this https://www.agro-k.com/. I think they have a Calcium phosphite for foliar spray.

SWD = White druplet syndrome, right? Sorry for being so slow.

Depends on the fungicide. Always avoid mixing with copper. Better check on label for compatibility.

I used to mix it with must fungicides with no problem. Aliette (fosetyl Al) is a fungicide with similar effect as potassium or calcium phosphite. So phosphite should aid in your phytosanitary program against disease acting as a fungicide.

SWD is a major pest of berries. Here’s a link: Drosophila suzukii - Wikipedia

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Thanks for the info. I don’t have a lot of disease problem so I don’t normally spray any fungicide after fruit set but fruit maggots (SWD) would be a disaster if I got them so I spray for those. It would be very little trouble to add something to the mix that would help with the white druplets too. I have used a potassium phosphyt product on apples and I will look to see if it’s labeled for blackberries

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Thank you for the clarification. Yes, we have here Drosophila sp. as well. Mites, thrips and others.

it is not the topic right here, but have you ever grown Obsidian, Metolius or Siskiyou blackberries in your farm?

I suppose these trailing blackberry varieties from Oregon require more than 800 chill hours?

I have never tried any of those but have been told by the “experts” that blackberries from the PNW do not do well in the southeast US where I live. The blackberries from Arkansas all do well here.

I have plenty of chill hours and should probably test some of these just in case the experts are wrong. Unfortunately, I’m old and out of energy so I’m cutting back rather than trying new things.

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Thank you. I have been told the same. However, I think Ollalie and other trailing (think Marion) will behave well under 400 chill hours. The issue is heat in the summer, I think.

I will give a try, if one of these work for me I will immediately share with you my experience.

I use diatomaceous earth in my potting mixes (the size of perlite) and it has large amounts of silicon which is a must in plant cell walls. Studies show that plants can access the silicon from DE too. That is not why I use it. I use it as it holds 120% of it’s weight in water. After saturated acts like perlite to drain off excess water. The pores are big enough for roots to access (unlike clay such as turface). So it gives me a day or two extra time before watering the pot, yet never causes a saturation problem. Anyway this too might help build strong cell walls. The studies indicate it most certainly does. Most soils already have a lot, but potting soil does not. Still it would not hurt nothing to try dry food grade DE powder for SWD and adding silicon to the soil to try and prevent the white drupes. If strong cell walls make a difference, this is the best way to make them strong. Some use this product

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I have a question about this white drupelet syndrome- does it make the taste of berries any different? I have seen it on occasion, but never noticed a taste issue. I only picked a small number though, the other berries were riper. By the time I got back the next week, it was a whole new variety we were on (this was a u-pick). I haven’t seen this on my own berries, but I will let them start fruiting this year.

Sunburn, usually first ripening berries are effected. Its less of a problem as others get ripe.