Excellent Powerpoint given by UC Davis' Marita Cantwell at Oleg Daugovish's caneberry meeting this past April.  Probably the best you are going to find anywhere concerning post harvest handling of these delicate fruits:

http://ceventura.ucanr.edu/files/188522.pdf

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.

Really nice video clip on the new Prime Ark 'Freedom' variety just released by John Clark from the University of Arkansas breeding program.  It's the first commercially available thornless primocane bearing blackberry.

Please take note growers that this variety is very much oriented to the home gardener and not intended for large scale production for shipping.

Very nice explanation too by Dr. Clark on the difference between primocanes and floricanes.  Have a look.

A cover crop can be a useful way to prevent weeds in anchor rows.

Cover crops in anchor rows can suppress weed growth and additionally help to minimize soil erosion and nutrient and sediment loss when it rains. Densely planted cover crops can outcompete weed seedlings germinating from the soil and prevent wind-dispersed seeds from reaching the wet soil surface. Have a look at the newly revised weed section in the Caneberries Pest Management Guidelines on the UC IPM web site. 

As readers know, tunnels used for caneberry cultivation have the advantage that even when it rains caneberries remain dry which helps with fruit quality and yield. However, during rains, the water drains from the plastic cover of the tunnel and down into rows that contain the anchoring posts of the tunnel structure. The accelerated runoff in these post rows can cause soil erosion, sediment and nutrient loss. As such, the persistent soil moisture in post rows also promotes weed growth.  These weeds, while maybe not competing directly with canes, can reproduce and quickly spread into neighboring cane rows.

Cover crops in the anchor rows are especially helpful when managing weeds that are difficult to control with fumigation because of their hard impermeable seed coats (mallows and filaree), or that have developed resistance to herbicides such as glyphosate and paraquat (hairy fleabane and horseweed).

Cover crops can be managed with mowing or herbicides to avoid seed production.