42 MASS. EXPERIMENT STATION BULLETIN 355 



kerosene into the soil where it can kill weed roots. This does not mean, however, 

 that flooding for protection from frost or for insect control shortly after the 

 kerosene is applied would render the kerosene inefTective, for the penetration of 

 this oil evidently is fairly rapid ur.der favorable conditions, and it is not easily 

 dislodged by water once it has reached weed sheaths or roots. If a bog is flooded 

 the night after kerosene is applied, the weeds affected by the oil die as quickly 

 and completely as they would without the flooding. 



4. Treatments with kerosene late in April killed the grass then showing green 

 above ground; but most of the perennial roots had not at that time grown tops, 

 so the grasses came in fairly thickly again later. 



The kerosene treatments in May seem to have given especially good results, 

 killing most of the grass and usually causing little vine injury. The normal 

 development of the vines and flower buds is often retarded two weeks by kerosene 

 applied in May, especially in late May. From the 10th to the 14th of May is 

 perhaps generally the best time for this treatment. A few of the tender runners 

 are burned by kerosene late in May, but growers agree that this injury, if coupled 

 with effective weed control, is negligible. Some growers reported complete destruc- 

 tion of crop prospects from kerosene spraying in the middle of May after late- 

 holding of the winter flood. Many and large test plots showed no difference in 

 cropping on untreated areas and areas treated with kerosene in Maj'. 



Treating bogs with kerosene in late June or in July is not advisable because 

 of the danger of serious injury to cranberry- vines and crop in those months. 



Kerosene treatments in August ruin the fruit but do not harm the cranberry 

 vines when carefully applied. Kerosene spraying in August and September has 

 the important advantage of reaching a maximum of weeds, for by that time 

 weeds in general are mostly grown for the season. More work is needed to deter- 

 mine whether kerosene treatments in late summer or early fall reduce the buds 

 for the following year. 



5. It was found safe to spray cranberry bogs with copper sulfate up to 30 

 pounds in 100 gallons of water in May as well as in August. This concentration 

 injured the vines greatly when used in June or July. 



The second or third week in August seems the best time to use the copper sulfate 

 solution, 20 pounds in 100 gallons of water, 400 gallons per acre, on nut grass 

 (Cyperus dcntatus). The nut grass is just as completely killed by this late spraying 

 as by earlier treatments and there is less chance of injury to the vines. 



Copper sulfate solution, 25 pounds in 100 gallons of water, 300 gallons per acre, 

 is the best spray found for killing beggar-ticks {Bidevs spp.) on bogs. It should 

 be applied about the middle of August. 



Copper sulfate solution, 20 pounds in 100 gallons of water, 600 gallons per acre, 

 applied late in April or early in May, kills hair-cap moss (Polytrichum) com- 

 pletely and seems the best treatment for it so far found. 



6. Dusting experiments with sodium arsenite were tried late in August. 

 The results were very encouraging, for all the wild bean {Apios tuherosa) foliage 

 was burned off^, 70 percent of the poison ivy plants lost their leaves, feather ferns 

 (Dryopteris) and Rtihus were defoliated, and Panicum agrostoides was burned to 

 a crisp. Little injury to cranberry vines was caused b}' either of the two dilu- 

 tions used: \^ pound sodium arsenite in 9}4 pounds gypsum, and 1 pound sodium 

 arsenite in 9 pounds gypsum. 



7. A solution of 100 pounds of sodium chloride in 100 gallons of water proved 

 to be a better treatment for wild bean and fireweed (Erechiites) than the one of 

 75 pounds in 100 gallons heretofore advocated. 



In the search for some chemical application which will kill all ^'egetation and so 

 prepare swamp land for setting cranberry vines, it was found that 4 tons of sodium 

 chloride per acre will kill 98 percent of the poison ivy and all other bog plants 



