Long Stemmed Weeds in my Blackberries and Blueberries

Asked May 1, 2013, 8:36 PM EDT

I hired a landscaper to put leafgrow in the garden where I am growing blackberries and blueberries. He had put the leafgrow in the same area 3 years ago and I have been very pleased with how well the berries are growing and producing. On March 30th he applied the leafgrow again for me. Since that time I have these huge weeds growing. When I tried puling them up I noted they have a long stem. I did not get to the actual root. I am attaching pictures. I would like to know what the weed is and how can I get rid of it. It is taking over. I have never put any fertilizer or weed killer in the area with the berry plants. I am desperate. I plan to also email the landscaper who bought and applied the leafgrow for his thoughts. I am very interested in your professional advice. He had also applied mulch in the rest of my garden and I am thankful to this time I have not seen that weed. I am attaching px of the weeds.

Baltimore County Maryland

5 Responses

The weed in your photo appears to be Canada thistle, listed as a noxious weed in Maryland meaning that landowners are compelled to control it. It is a perennial weed that reproduces via seed and new plants that emerge along underground stems (rhizomes).

The key to control is vigilance and persistence. Mowing/clipping the tops whenever they appear will also help starve the roots. Using a small paint brush to apply a non-selective herbicide to the cut ends of the top growth will further help to suppress/kill the plants. Repeated tilling- every 10-14 days will deplete the food stored in the roots. But if done less frequently the re-growth will strengthen the root system and encourage further spread. Tillage here definitely means using some type of tiller or turning AND chopping the soil and rhizomes.

Hand-pulling very young plants is ok but hand-pulling older plants leads to new plants. You think you are getting a lot of root, but most stays behind. New plants emerge from the broken root ends. I’ve seen people try to smother it with weed barrier with very limited success. JT

Thank You for your immediate response. I am a senior and put a good bit of money into the application of the leafgro. I have notified the landscaper of the problem and your response. Waiting for a reply.
Please tell me what kind of herbicide can be painted on the stem after cutting at ground level. It has to be safe because of the berry plants right next to the weeds.
Also I fear those strong roots could kill the roots of the berry plants.Is that a possibility?
Await your answer. Thank You for your sharing your expertise.

Glyphosate or RoundUp can be painted directly on the thistle. Be very careful not to get it on your fruit plants. Follow directions on the label of your herbicide. More than one application may be required. If the thistle is allowed to grow, it will compete with the fruit plants, but will probably not kill them totally. It will be important to remove the thistle, especially before it goes to seed. vw

In response to you suggesting ruondup. I am familiar with roundup and it says you put it on top of plant it wil go down to root and kill it. That scares me that it could go to the berries.
Is there any organic herbicide?
Also if the landscaper comes back and digs up the roots do you think that would stop the growth and spread.?
Thank you for you information. I really apreciate your knowledge.

RoundUp will only affect plants that the liquid actually touches. It will not go into the soil and from there into roots. That is why we emphasized not getting glyphosate on the berry bushes. If the glyphosate gets on the soil, it will not be taken up into the berries. There are no effective organic controls. If you dig up the thistle, it is possible that the entire root will not be dug up. A piece of thistle root is capable of growing into a whole plant. If the plants are dug up, some will probably regrow. Persistant removal of plants either by digging or glyphosate will be necessary.