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Blackberry Cane Blight

I've been infected!

Watching the canes of different berry plants come to life in spring, in my opinion, is an incredible thing to witness. How something can go from a dark colored, solid, woody texture during the winter to a softer, light brown, cane full of life shows how complex nature can be. Blackberries in particular are fun to watch, but they are not to be taken lightly. Without proper management, diseases like orange rust, powdery mildew, and cane blight can destroy your hopes for a large crop of berries for the year. Oftentimes you will not know that you even have a problem until the season is in full swing. This has now happened to me. Cane blight has infected nearly all of my canes and I plan to share why I think it happened, what it looks like, and what I hope to do about it.

 

What happened?

 

There is one MAJOR lesson I have learned first hand when it comes to cane plants and tree management. A lesson that I’m sure I read or heard somewhere and had it go in one ear and out the other. Most of us understand that in order to get great harvests and have healthy blackberry plants, you need to prune. Pruning encourages heavier fruiting, it creates better airflow which prevents diseases, and it focuses energy on the existing canes to make them grow stronger. With blackberry plants, you want to do your heavier pruning in the late winter when the plant is dormant, preventing unnecessary damage. Everything about pruning is positive, unless you forget the number one rule.

 

Rule #1: ALWAYS clean your pruning shears with an alcohol (70-90%) and bleach (10%) solution before moving onto the next cane/plant.

 

This will kill pathogens and disease, preventing the spread to other canes and plants. If you do not do this, the risk of ruining ALL the plants you prune increases drastically. Trust me, I know because this has happened to me.

I did some pruning in early winter when the canes may not have been fully dormant. Normally this isn’t to much of an issue, but with canes (and potentially diseases) not quite dormant, sharing problems is more likely. As with many things, once I get going with something I generally don’t stop until it is complete and before I knew it, I had pruned all four of my blackberry plants. Nothing seemed out of the ordinary at the time and so I left them to ride out the winter. Come the beginning of spring, I noticed something odd about my plants. Instead of being a nice brown color, many of them had large gaps of discoloration.

As I looked more closely I began noticing that it was not just one of my canes that seemed to have issues, it turned out that nearly all of them did. I had unintentionally spread the disease from cane to cane! At this point I did not know what it was. Just like many people do when they are experiencing problems, they turn to Google for answers. I did what you may call a WebMD for my blackberries and found that I am experiencing Cane Blight.

 

What it looks like.

 

If you look at the Wisconsin Horticulture site (a UW-Wisconsin Extension) it goes through and explains each of the symptoms in detail. First defining cane blight as a fungal disease that infects blackberries and red raspberries. Then listing out what to look for to determine if this is what ails your plants.

    1. Death of side branches and tips of fruiting canes.

Looking closely, a number of side branches appear dead and even the tips of others are in rough shape as well.

 

    2. Dark brown or purple spots (cankers) below the die back.

You can see dark brown spots leading into the discoloration as you travel up the cane.

    3. Grey Ooze in wet weather, fuzzy or powdery in dry weather.

When this photo was taken, the weather had been somewhat dry and the cane looks as if it has a white powder all over part of it.

    4. Canes become brittle and snap off easily.

It’s really hard to demonstrate the brittleness of the side shoot below, but I will assure you had I tried to break it, it would snap very easily.

 

What to do?

 

You must be thinking, “are you going to have to dig them out and start all over”? This is exactly what I thought at first and was pretty upset since blackberries can take a couple years to start fruiting consistently. Luckily, it does not seem like that is what I’m going to have to do.

To manage this plague, I will first mark each cane that is infected to be pruned away when the plant is dormant. Doing this in the winter will let the cuts heal up before spring and will prevent the fungal disease from spreading to new canes. No pruning will happen during the year on these canes. Clean those pruners after each cane or plant!

Secondly, I must make sure to keep the plants tame so that good airflow can pass through. Trellising them up like I do is one way, but proper pruning will ensure that this fungal blight will not fester and grow again. The new canes that are coming up look healthy so far. Maybe there is light at the end of this tunnel.

I expect there to be some berries produced this year, but not nearly the amount as last year. Sometimes you have to take the good with the bad and hopefully you can learn from my experience and prevent the contraction and spread of Cane Blight with your blackberry plants.

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About the Author

Geoff has been growing plants and vegetables consistently for the last 6 years and actively experiments with, and writes about, all aspects of gardening.

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