102 MASS. EXPERIMENT STATION BULLETIN 252 



of personal judgment, however careful the observations. Most of the 

 experiments cited apply to foliage having a thin cellulose or cutinized 

 epidermis, and those pertaining to waxy leaves and fruits are so design- 

 ated. The theory that "like attracts like" may have unduly influenced 

 practice in some instances. 



Attention is called to the results of other investigators. Recent data 

 on sugar and dextrin have been seldom noted. The use of saponin to 

 increase spreading was probably first recommended by Gastine (32) and 

 later by Chappaz (13) and Lafforgue (50). Cactus (Cereus) extract, con- 

 taining cactine, apparently has a similar action and was found by High 

 (42) to increase the spreading of arsenites. Irish or Pearl moss (Chon- 

 drus), so-called carrageen, was employed by Issleib (46) and, according 

 to Stearns (86, p. 9-13), facilitates the distribution of arsenicals. Lovett 

 (58) found that sage tea increased the spreading of arsenicals on plain 

 but not on waxy surfaces (59). Verniorel and Dantony (94) claim that 

 0.05 per cent of casein increases the spreading of Bordeaux on grape 

 vines, and Stearns (86, p. 9-13) and Smith (85) that calcium caseinate in- 

 creases the spreading of lead arsenate. Some workers report casein of 

 0.003 to 0.03 per cent (probably with alkali) an eflfective spreader. David 

 (78) employed 0.75 per cent of glue with Bordeaux but later (63) decided 

 it was of no particular value. Lowe (60) states that glue increased the 

 spreading of lead arsenate. Hawkins (40, p. 22-25) found that 0.50 per 

 cent of glue, fish-oil soap and rosin fish-oil soap reduced the surface tension 

 of Bordeaux 4-2-50 and their eflficiency increased in the order named. Gal- 

 loway (28, p. 220, 221; 29, p. 202, 203, 213; 30, p. 131), Fairchild (24) 

 and Swingle (87) found soaps increased the wetting and spreading of 

 copper fungicides, and Washburn (95) that 1.50 per cent of while-oil 

 soap increased the spreading of Paris green and apparently the adhesive- 

 ness. Trappmann (89) found soap the cheapest wetting material but un- 

 safe to use with arsenicals. Sodium oleate and sodium resinate are occa- 

 sionally suggested as substitutes. Various earths and other inorganic sub- 

 stances have been used but proved of little value as spreaders. 



Oil emulsions, soap emulsions of creosote and saponin emulsions of 

 creosote (32) are said to increase spreading on all surfaces but are seldom 

 employed with copper fungicides. Pickering (74, p. 2010, 2011; 2, p. 29) 

 recommended a stable emulsion prepared from copper sulfate, calcium 

 hydroxide and a high-boiling distillate, but data relative to its eflficiency 

 are not available. Winston, Bowman and Yothers (97) claim that 1 per 

 cent of oil emulsion with Bordeaux 3-3-50 increased spreading on citrus. 

 Moore (64, p. 18, 19) found beechwood and coal tar creosotes, phenol 

 derivatives, such as carvacrol, eugenol and xylenols, and amyl and benzyl 

 alcohols excellent for waxy surfaces. 



Among the points that should be considered are compatibility with the 

 fungicide, effectiveness in wetting and spreading, ease of preparation and 

 cost. The evidence presented is drawn from special experiments with 

 basic copper sulfate by Dr. E. F. Guba of the Market Garden Field Sta- 

 tion at Walthain. He employed cucumbers and tomatoes In the green- 

 house and cucumbers and celery in the field. The amount of substance 

 added is reported on the basis of the spray— 0.10 per cent is equivalent to 

 3.8 grams (0.13 oz.) to an American gallon, or 188.5 grams (6.65 oz.) 

 to the barrel. He found that basic copper sulfate had rather poor wet- 

 ting and spreading properties as compared with Bordeaux 4-4-50. With 



