The applicator carries the light pistol-type spot gun in one hand (Figure 10). The gun is attached by plastic tubing to a 1-gallon, hand-held container. As with basal dormant spraying, selection of a winter day with a light dusting of snow allows foot tracks to determine which bushes have been treated. Labels permit applications to frozen ground as long as snow or water does not prevent proper placement to the soil surface. On sloping ground, the herbicide should be placed upslope from the plant crown wherever possible. With larger plants, divide herbicide between two or more places near crowns to intercept more roots.
Two herbicides are labeled for dormant spot concentrate applications: dicamba (Banvel) and metsulfuron methyl (Escort only, not Ally). Banvel is labeled for use in pastures. Both of these herbicides should be applied after soil temperatures drop below 40 degrees F and before multiflora plants initiate significant spring leafout. Application when soil temperatures are low is especially important with Banvel to inhibit breakdown by soil microorganisms before proper root uptake by rose plants. Reduced effectiveness of Escort when applied after leafout suggests breakdown in soil is also a concern with this herbicide. Banvel is applied undiluted, based on plant canopy diameter (see Table 5). Do not exceed 2 gallons of Banvel per acre with this technique.
|Table 5. Banvel spot concentrate application rates|
|Plant canopy diameter||Banvel (4 DMA) needed|
|English or metric|
|5 feet||1/4 oz = 7.4 ml|
|10 feet||1 oz = 30 ml|
|15 feet||2 1/2 oz = 74 ml|
Escort solution is prepared by mixing 1 ounce (29.6 gms) of Escort 60% DF with 0.3 ounce (10 milliliters) of nonionic surfactant in 1 gallon (3785 milliliters) of water. Agitate the container occasionally during application to keep herbicide in suspension. Apply this solution to the base of plants at the rate of 8 milliliters for each 2 feet of plant canopy diameter. Prepare fresh mixture daily because metsulfuron methyl gradually breaks down in water by hydrolysis.
While acceptable results generally occur with application of these products to dormant rose, occasional instances of unsatisfactory control have occurred (see Table 6). Because root uptake is involved, lack of precipitation after application may occasionally inhibit movement into soil and reduce efficacy.
|Table 6. Multiflora rose control in Ohio winter field trials of dormant spot-applied herbicides|
|Product||Number of trials||Mean BRR rating1||% of trials with complete plant kill|
|1. BRR (basal resprout rating) where: 1 = none, 2 = slight, 3 = moderate, and 4 = extensive basal regrowth 8 to 15 months after application.|
Note that these two products provide similar results across many trials (Table 7). The degree of plant kill with Spike 20P is inferior to results with previously mentioned spot concentrate soil treatments. As shown in Figure 11, Spike 20P provides the most consistently effective control when applied during winter months.
|Table 7. Multiflora rose control in Ohio with Spike 20P and Tordon 10K pellets1|
|Product||Number of trials||Mean BRR rating2||% of trials with complete plant kill|
|1. Data for both represent January through mid-September application dates.|
|2. BRR (basal resprout rating) where: 1 = none, 2 = slight, 3 = moderate, and 4 = extensive basal regrowth 8 to 15 months after application.|
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