- Author: Mark Bolda
- Author: Steve Fennimore
- Author: Patrick Kingston
Field bindweed, Convolvulus arvensis, also known locally as morning glory, is a persistent weed pest in blackberries grown on the Central Coast of the California. Much of this stems from the long period of time between plant establishment and final removal of the crop some five to six years later.
While cultivation of the aisles between the hedgerows is successful in keeping the field clear of most weeds, field bindweed is another matter. Not only does field bindweed establish very deep root systems which frustrate control by cultivation, but the lengthy vines of this plant grow into the hedgerow and even up onto the plants themselves (Photo 1). Spray applications of translocated herbicides like Roundup are risky due to sensitivity of blackberry to spray drift. For this reason we have selected ropewick application methods to reduce the possibility of spray drift and crop injury.
The study described here is an experiment of two methods of wick applications of glyphosate (Roundup). One method, pictured below, is of a ropewick applicator (Photo 5) which applies a 33% volume per volume (v/v) dilution of formulated product through the ropewick applicator directly to the bindweed leaves by briefly passing over the area in a purposeful back and forth swinging motion. The second method, used occasionally on woody vines which die slowly, was to clip approximately 1”x1” sponges soaked with a 33% v/v dilution of formulated product with colorful refrigerator magnet clips to individual bindweed leaves (Photo 3). In both cases, great care was taken to avoid contact with blackberry plant parts, especially canes hanging down close to the ground. Please note – blackberry is very sensitive to Roundup (Photo 7) and contact with foliage must be absolutely avoided.
As can be seen from the pictures below (Photo, 3, 4 and 5), after two weeks both methods are quite effective in controlling field bindweed in blackberries. It should be noted that the clip method, while quite effective in controlling field bindweed, is far more time consuming than the ropewick applicator and not recommended.
It is lastly important to note that regular retreatment of the field bindweed especially in the fall will be more successful with the ropewick method described here. One should treat regularly but not too frequently and every month to six weeks should work. Let the bindweed regrow some, since it is going into the fall and it is storing starch reserves for its roots. As the bindweed makes sugars in its leaves it is sending that sugar downward into its roots deep in the ground, and this is the time to send some glyphosate into those roots. These roots are the bindweed wheelhouse and this is where to hit it where it hurts.
The use of glyphosate (Roundup) is extensively written about in this article. Before using any of these products, check with your local Agricultural Commissioner's Office and consult product labels for current status of product registration, restrictions, and use information.
- Author: Mark Bolda
This comes up a couple of times every year so it is worth reviewing and certainly adds value to our catalogue of plant disorders on these berry blogs.
The following plant sample of a proprietary variety was received 4/24/2012. One can see immediately that the leaves are chlorotic and burnt at the margins and in some cases (photo 2 below) newer leaves are somewhat deformed as well. Most often one will encounter a pink tint to many of the leaves.
The situation in the field was as follows, a mixture of Round Up (glyphosate) and Shark (carfentrazone) was applied to the field to control weeds one month prior to planting. According to weed scientist Steve Fennimore, the Shark does not linger in the soil for any significant period of time, actually around three hours tops. On the other hand, Round Up can linger for a while, maybe even longer than a month especially in a sandy soil in which it is not adsorbed to fine soil particles as it would in a clay.
The solution to this predicament, and indeed in all cases of Round Up toxicity, is to let the plant grow out of it. Raspberries have substantial stores of carbohydrates to draw on and can usually overcome the temporary inhibition of photosynthesis caused by mild herbicide damage such as the case presented here.
There are several herbicides mentioned in this article. Before using any herbicides, check with your local Agricultural Commissioner's Office and consult product labels for current status of product registration, restrictions, and use information.