Weed Management Options In Blueberries
Establishing and maintaining an effective weed management program is one of the most important factors in obtaining optimum commercial blueberry yield and quality. While insects, plant pathogens and other pests occasionally attack commercial plantings, a blueberry producer can always expect weed pressure to be a challenge, no matter what production system is being utilized.
Blueberry growers who initiate planning their weed management program long before establishing a new planting or rejuvenating an established field or farm will have the highest probability of efficiently managing these pests. The following sections will describe some common weeds encountered in Florida Blueberry Farms and tactics that will assist growers to manage weed populations in their farms.
In organic production, weed management is often a very costly operation, as there are a very limited number of herbicides approved for organic production. The herbicides that are available are often very costly and have limited efficacy, as they mainly burn the actively growing plant tissue on which they are applied. For these reasons, it is essential for organic blueberry producers to take all steps necessary to prevent weed infestations from becoming established.
Proper Weed Identification
As with any pest a blueberry grower encounters in their field, proper identification of weedy species present in the field is the first step to initiating a successful weed management program. Once a grower identifies a weed species, he can obtain information about the time of year to expect it to infest his fields and what control tactics will be effective in its management.
Types Of Weeds Encountered
Perennial and biennial weeds – Perennial weeds are those that can survive for several years. These weedy pests may be present all year or be dormant during the winter, only to begin regrowth with the advance of warmer temperatures in the spring. An example of a perennial species which can be a weedy pest of blueberry farms is common Bermudagrass (Cynodon dactylon). Bermudagrass can often be a serious pest when new blueberry fields are established in old pastures or hay fields.
Some other common perennial weeds encountered by blueberry growers:
- Yellow (Cyperus esculentas)
- Purple (C. rotundus)
- Green brier (Smilax spp.)
- Curly dock (Rumex crispus)
- Red sorrel (Rumex acetosella)
Biennial weeds complete their life cycle in two years. Typically in the first year they have low vegetative growth when a deep taproot is generally formed, followed by the emergence of a flowering shoot in the second year.
Some biennial weeds that may be encountered in blueberry farms are:
- Wild carrot (Daucus carota)
- Carolina false dandelion (Pyrrhopappus carolinianus)
- Common mullein (Verbascum thapsus)
Annual weeds – Annual weeds establish and generally complete their life cycle in a 12 month or shorter period. Annual weeds often can be separated into two groups; summer and winter annuals. Winter annuals are those that many blueberry growers encounter from the dormant period through harvest. Summer annuals are mainly a pest from post-harvest through the fall.
There is typically a diverse mix of mainly broadleaf winter annual plants infesting Florida blueberries. Some common winter annual weeds observed in commercial blueberry plantings:
- Asiatic hawksbeard (Youngia japonica)
- Carolina geranium (Geranium carolinianum)
- Cudweeds (Gnaphalium spp.)
- Cutleaf eveningprimrose (Oenothera laciniata)
- Oldfield toadflax (Linaria canadensis)