22 N. H. AGR. EXPERIMENT STATION. [Bulletin 203 



Plot 7 — 20 tons manure per acre. 



1000 lbs. muriate of potash per acre. 

 Plot 8 — 20 tons manure per acre. 



500 lbs. acid phosphate per acre. 



500 lbs. muriate of potash per acre. 



In 1920 there were two dupUcate plots of each treatment, and in 1921 

 there were four. Records of the number of fruit and weight at each pick- 

 ing time were kept for each plant. The number of blossom clusters, the 

 number of blossoms per cluster, the mmaber of fruit set and the number of 

 fruit dropped were recorded for 12 plants of each plot. This data is being 

 tabulated and analyzed, and will be the subject of a later report. 



Immature Forest Stands. 



The sample plots of important economic forest trees were remeasured by 

 K. W. Woodward (P^orestry) who has a detailed statement of the results 

 in preparation. It will be unnecessary to carry further the series of experi- 

 ments designed to determine the effect upon white pine reproduction of 

 overtopping by hardwoods. It has been shown conclusively that the hard- 

 woods must be removed before the end of the first ten years or the pine will 

 die. 



Definite results have also been obtained as to the best methods and costs 

 of lopping hardwoods. 



The plots devoted to growth studies will be continued. These include 

 the following species: white pine, Scotch pine, red pine, European larch, 

 Nonvay spruce, Douglas fir, and white ash. 



To replace the plots which have served their usefulness new ones intended 

 to give data on the thinning of immature pine stands are being established. 



Spraying for Apple Maggot. 



In order to determine the efficiency of spraying with arsenate of lead as 

 a means of control of the apple maggot under New Hampshire conditions, 

 Mr. O'Kane has conducted further experiments in the crop seasons of 1920 

 and 1921. Experiments recorded in an earlier bulletin of this station gave 

 negative results from spraying with a poisoned bait in which arsenate of 

 lead was added to sweetened water, with the intent of attracting the flies 

 to the drops of bait. The present experiments follow the plan of spraying 

 a large area, leaving no checks, and using a simple mixture of arsenate of 

 lead and water without the addition of sugar or other bait. The intent is 

 to secure such wide distribution of the spray that flies feeding on the leaf 

 surface will be poisoned. This is the basis of the spraying schedule recom- 

 mended for the apple maggot in two or three other states. 



Under New Hampshire conditions the experiments carried out last season 

 gave negative results. The work of this season is inconclusive, because of 

 a lack of abundance of the species in the areas under observation. 



Control of Black Flies. 



The experiments carried out in former years were continued by Mr. O'Kane 

 through the present season. In addition, an increased number of collections 

 were made at various points in New Hampshire, and the distribution of the 

 various species was studied. Important observations were begun on the 

 hibernating habits of these insects. 



