Raspberries and other caneberries are prized for the large number of flavorful fruits they can produce. A number of factors can negatively impact raspberry yield and fruit quality, including moisture stress; inadequate or excessive nutrients; pests or diseases; and weeds that compete with the raspberry canes for water, nutrients, and light. Weeds near plantings can also harbor potential raspberry pests and diseases. Clearing an area of weeds and weed seeds prior to establishing a raspberry planting can reduce the presence of weeds for several years, but weed control around established canes is still eventually necessary. Here are the steps,
1. Pull small weeds up by hand, or shallowly cultivate the area with a hoe or similar implement. Break up no more than the top 2 to 3 inches of soil, and leave ample space around the canes to avoid accidentally injuring the canes or roots.
2.Spread 3 to 8 inches of an organic material mulch like dry grass clippings, shredded leaves or straw between the rows and plants. The thickness of the mulch layer should vary depending on the material. For example, a 6- to 8-inch layer of straw is needed to effectively block weeds, while 3 inches of sawdust may perform equally well.
3. Spray a non-selective herbicide such as glyphosate only on the weeds, taking care to avoid contact with or drift onto raspberry canes or any other desirable vegetation. Alternatively, you can apply a herbicide that contains paraquat or carfentrazone to the entire mature raspberry stand to control weeds and green, first-year canes.
4. Mow, trim, pull or use a non-selective herbicide such as glyphosate to address weeds near the raspberry planting or garden before they go to seed or, in the case of creeping perennial weeds, grow into the planting.