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WICHE: Do you have problems with bramble?

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By Jeneen Wiche

So much for the raspberries this year. Not the best crop we’ve seen. In fact each year it seems to get a little messier then the last.

We typically cut the “Royalty” raspberries all the way to the ground each year and forgo an early crop to manage disease, but it doesn’t seem to be working that well this time around.

It has not been a total loss, but about half the canes are dried up and diseased.   

One problem that has materialized is a condition called “doubles,” which is caused by a virus, as are most bramble troubles. There is nothing you can do about it except practice good bramble management.

Viruses have a tendency to get worse year after year so the best management practice is to clean away old plant debris and cut the canes all the way to the ground each fall after harvest. 

The University of Kentucky Plant Disease Diagnostic Laboratory has received a high number of bramble samples this year, which suggests we are having a very viral year.  Problems include die back, sterility, poor fruit set, misshapen fruit, small fruit, and crumbly fruit. 

UK Plant Pathologist John Hartman says that these failures may be caused by several different problems.

First he says assess the cultural of your bramble patch.  If the soil, sun, air circulation, water and weed control is sufficient, you can look to some other causes for disease.

If your brambles have been around for a couple of years and never fruited, you have a rogue raspberry or blackberry. Some sort of hereditary problem in the plant has rendered it useless, and you should get it out of the garden because it won’t do anything but take up space. 

The cool, wet spring means we may see problems with anthracnose on brambles, which would also cause problems with poor fruit set.

If the plants have fruited in the past but did not this spring, it may be the fungal disease anthracnose.  The canes of the plants will develop lesions and cankers later in the season, so the best bet at this point is to remove all the canes in order to remove the disease.

There is always next year.

 

Virus diseases include raspberry mosaic virus, raspberry leaf curl virus, tobacco streak virus, and tomato ring spot virus.  The mosaic virus causes stunted growth of plant, which gets worse by the year, mottling and blistering of foliage and crumbly berries. 

The leaf curl virus causes the foliage to curl downward and loose the downy appearance of the foliage (instead it looks dark and oily).  This disease also causes fruit to be small, seedy and crumbly.

Tobacco streak virus causes the foliage to be deformed and yellow-streaked, and tomato ring spot shows up in pale yellow spots on the foliage.

It is pretty easy to tell when the bramble patch is doing poorly, and unfortunately there is not that much we can do.

I think I can find a representation of each of the virus diseases in our raspberry patch in the garden. The ”Hull” blackberries still look clean, thank goodness.

Because these viruses have the potential of getting worse over time, we will be monitoring disease activity from year to year, and we will cut the plants all the way to the ground after harvest.

I think ours have nearly run their course, however. We will also keep wild brambles out of the area and keep weeds to a minimum, because they can act as disease vectors spreading them to our cultivated patch.

We started out with certified disease-free plants, which is a must, but once they are in our garden, it seems like it is only a matter of time for a virus shows up.

Hartman warns if you have consistent problems with sterility and signs of disease, you should remove the brambles and burn or dispose of the debris.

Grub out any roots and do not replant brambles in the same location for several years.