In the Connecticut studies, clear plastic permitted weed growth that was 

 mentioned as an objectional feature. In limited trials with clear plastic 

 under apple trees in Massachusetts, it was found that the grass and broadleaf 

 weeds were controlled during the summer months. During cool weather growth of 

 grass and broadleaf weeds was stimulated. Whether the competition of the grass 

 and broadleaf weeds during certain periods of the growing season is sufficient 

 to have a detrimental effect on tree growth is not known. 



Other questions pertaining to the use of small plastic sheets under apple 

 trees remain to be answered. What is the effect of plastic mulches on the 

 rooting habit of apple trees? Research with tobacco and other crops has shown 

 that under plastic mulch, root growth near the surface was appreciably greater 

 but root extension at deeper levels was not affected. 



\-Jhat is the effect of plastic mulches on tree growth? Will the higher 

 soil temperature under clear plastic have an effect on tree growth in 

 comparison to black plastic or hay mulch? 



Until more is known about plastic for mulching apple trees, it is 

 suggested that black plastic may be tried under nev<7ly planted trees if 

 insufficient hay mulch is available to suppress grass and broadleaf weed growth. 

 After the trees have been established more than a year in the orchard, the 

 grower has the choice between black plastic, hay mulch or herbicides to con- 

 trol grass and broadleaf weeds. When hay mulch is available, it remains the 

 number one recommendation. 



* * * * 



POMOLOGICAL PARAGRAPH 



Plastic for Mulching Under Apple Trees 



William J. Lord 



There is grower interest in the use of black plastic as a means of weed 

 control under apple trees. Black plastic is now available in rolls of individ- 

 ually serrated squares with each square perforated to facilitate placement 

 around the tree trunk. 



How much of a problem mice will be under the black plastic is not known - 



reports have been conflicting in this regard. We are trying to at least obtain 



a partial answer to this question in a demonstration experiment comparing black 

 plastic with hay mulch. 



Placement cost will at least equal that of the material assuming that 

 36" X 36" squares are used. A report from New Jersey indicated that 3 men 

 were able to place the plastic squares at the rate of thirty trees per hour. 

 T^^o men placed the squares and a third man covered the edges with soil. 



In our mulching demonstration, one man unrolled the plastic and ripped 

 off the squares. One man ripped the serration in the middle of the square 

 and placed the plastic around the tree. A third man followed and pinned the 

 4 corners of each square into the soil by placing the point of a shovel on the 

 plastic and thrusting it into the soil. Gravel which was hauled into the or- 

 chard was then placed on the edges of the plastic. Not taking into account 

 the time necessary to get the gravel, 3 men were able to place 40 plastic 



