Diseased Sloes in New Jersey

Wrenchbender

I’ve spent many years trying to start blackthorn here in New Jersey. It is not a native species but it does exist but is very difficult to find in the eastern U.S.  I got lucky with some saplings from the state of Oregon. Previous attempts failed because the local whitetail deer seem to enjoy the young plants before they develop thorns. I finally have six substantial plants nearly ten feet tall and they’ve produced fruit for three years. From the beginning, I’ve had some sort of disease problem with the fruit. It started with the first small harvest with many of the sloes initially developing well but in September, half of them interrupted their development to shrivel up. Last year I addressed a severe case of aphids, treated with dilute neem oil and also an anti fungal spray due to some sick branches. This year, I treated with a copper based anti fungal spray right before blossoming in spring. Everything was indicating a bumper harvest with happy sloes until three weeks ago late August. I started to see signs of the skin on the fruit dimpling. Today, 90% of the fruit is sick. Its early in the year with night time temps in the low 70sF at best. I picked what I could. Its a big loss. There is absolutely no knowledge of sloes here. I’m hoping someone might recognize the problem. Even the very tall branches that are alone, well elevated, uncrowned, and away from the plant have the problem. My blackthorn gets full sun from 9am until 7pm. Rain has been good this year and generally the plant thrives early in the year until the end of August and even with the failing fruit, most of the plant looks very healthy. There are a couple patches here and there with leaf stress but even in the very healthy sections, the fruit is corrupted. Where there is good fruit, it’s congregated together while on the same limb, there is corrupted fruit.

fidgetbones

I've no idea of your climate. Maybe it doesn't grow well because conditions don't suit it. I know that here in the Midlands of the UK,  Blackthorn plants itself(bird droppings/squirrels etc)  grows in  hedgerows and woodlands, gets pruned/hacked to hedge shape or not depending on the farmer/landowner,  and never gets sprayed with anything.  It usually yield copious amounts of fruit, and after the first frost, locals go to pick the sloes  to use for sloe gin. Any left the birds have.  Maybe you are being too kind to it, and it is growing soft and weak, or the conditions you have are just not right.

Wrenchbender

Thank you for some discussion. As far as the climate, it’s much like the UK but with a bit colder winter and more humidity in the summer. I lived in the UK for 16 years and we have just slightly more of a swing between the seasons but I have seen the UK get just as cold and lately, just as warm. First frost may be as late as December. Since it started fruiting, it is actually self seeding new plants near and around the base. The difficulty is that no one really cultivates sloes so nobody ever has a reason to become an authority - like dandelions. Its a very disappointing harvest as I wish to introduce all of my friends to the joy of homemade sloe gin. There are funguses/blight here that assault cherries and plums with the only cure being destruction of the entire plant. I’m hoping that what I have is manageable.  

Pete.8

It cannot be relevant, but where I live there are hundreds of blackthorn bushes around here. They're normally laden with fat berries at this time of year, every year.
But this year there are almost none.
Every Spring there are so many flowers they look like white clouds, the berries begin to form, then this year they just vanished.
Most of the bushes now have just a few berries here and there.
I can only assume that it must be related to the unusual weather we've had this year.

Dovefromabove

You mention humidity … as you’re probably aware that doesn’t feature often in UK weather… but it has been humid here of late this year … I suspect that it may not be to the Sloe’s liking. 

Nollie

Blackthorn grows in and around my property with abandon here in my part of Spain with no care whatsoever. We have very frosty mountain winters and extremely hot, humid summers. The bushes in more dry, exposed positions provide very few berries. However, there are normally plenty to pick for slow gin-making - in the cooler, moister hedgerows.

In drought years, berries are far fewer and shrivelled.

I’m 100% sure it’s not a disease, so hold those sprays! Your bushes are simply just not getting enough water to swell the berries at the critical time.

Fairygirl

I'd agree with @Nollie. It's far more likely to be lack of moisture just when it was needed. I've got loads of berries, but I'm in the process of removing all the hedging as it's far too vigorous for my site. It doesn't have the best conditions for a hedge, but that moisture means it's always grown very easily - too easily. 
Our frosts normally start around the beginning of October, although recently there has been some [further north]  and we've had 5s and 6s overnight, which isn't unusual.  Frost, and colder weather, has no effect on them though, other than slowing the start to growth in spring, but we have consistently moist conditions in this part of the country, so the fruits swell and mature very readily. Humidity isn't very common here, even when it's been more thundery, as it was during August, but I doubt if that's a problem, especially as Nollie has indicated above the type of summer there in Spain.
Your temps are much higher than mine @Wrenchbender . 70 F/20-ish C, is very, very high for an overnight temp. We'd be really impressed if we got that during the day here at this time of year!

Wrenchbender

Water is a thought but it hasn’t been a dry year. Half of the rain here comes from fairly violent thunderstorms. June and early July were dry but at the moment, everything is lush and green. Next year I’ll keep an eye out and water when we go a few days without rain. The earth here is mostly dirty sand with a clay deeper down as I live in what is referred to as the Pine Barrens. Water drains away quickly so I’ll consider supplemental watering when we go more than four or five days without rain. Maybe the fruit gets damaged early in June and what I see now is the result. 

raisingirl

RHS say it's susceptible to aphids (you found that out for yourself), caterpillars and bullfinches - what you describe doesn't sound like those. It also says it may suffer from silver leaf and blossom wilt. But you say the leaves aren't being particularly affected. It is a high risk host for xylella, which I think is endemic in some parts of America, but not sure if it is near you?

Wrenchbender

Thank you all for wonderful discussion. I miss Europe and the UK very much. I’ll add that I’m amazed at how fast my six blackthorn have grown. And now they are propagating baby blackthorns which I need to transplant to extend what might become a hedgerow of sorts - much better than a privacy/security fence. They started five years ago and now they have branches nearly ten feet in the air. When the fruit does mature, they are actually a lot more sweet than sour. I was able to pick two pints so there will be sloe gin come February. There just seems to be such a loss of fruit which appeared to be healthy until recently. I’d love to try to make jam. 

Pete.8

When I used to make sloe gin I waited until the sloes got frosted - it seemed to make them a bit sweeter and a little softer.
Some years now we don't even get a proper frost anymore in winter.

I did read they can get Taphrina pruni so maybe worth checking that out