432 



STATE BOARD OF AGRICULTURE. 



4. Placed the fourth lot, of 5000 eggs, in 1-25 solution of 40% for- 



maldehyde for forty-five minutes. 



5. Placed tlie fifth lot, of 5000 eggs, in 1-10 solution of 40% formal- 



dehyde for thirty minutes. 

 G. Placed the sixth lot, of 5000 eggs, in 20%, CuSO, for thirty 



minutes. 

 7. Placed the seventh lot,' of 5000 eggs, in 1-50 H.SO, for thirty 



minutes. 



The results of this experiment are given in Table XV. 



TABLE XV.— ACTIVE LARVAE OBSERVED. 



Treatments 

 March 30. 1914. 



1. Lime-sulfr. 31-32° B. 



2. "Black Lf. 40" full 



strength 



3. Formaldehyde 1-100. 



4. Formaldehyde 1-25 



5. Formaldehyde 1-10 



6. CuSO4 20% 



7. H2SOa-50 



April 6. 



Abundant 



None active 

 Abundant 

 Abundant 

 Abundant 

 Abundant 

 Abundant 



April 7. 



Abundant 



None active 

 Abundant 

 Abundant 

 Abundant 

 Abundant 

 Discontinued 



In the case of the lime-sulfur and the "Black Leaf 40" treatments, 

 the smaller number of active larvoe recorded was due to the fact that 

 the medium was so clouded by the treatments that larvae could not be 

 distinguished unless they crawled up on the sides of the tubes above the 

 substratum. From the result of this experiment, it would seem that the 

 longer exposure to the chemicals does not affect the ability of the eggs 

 to hatch. 



In attempting to subject the eggs to the same conditions that they are 

 under in the actual soil treatments, it would appear that they should be 

 exposed to the chemical for only a short time. In soil treatments we 

 cannot conceive of the eggs being subjected to the chemical except just 

 during the period when the solution is passing down through the soil 

 directly after being applied at the surface. The various vapor treat- 

 ments are exceptions to the above statement because they exert an influ- 

 ence throughout the time they are present in the soil. 



SUMMARY OF THE LABORATORY EXPERIMENTS. 



Although the number of experiments conducted so far is not great, the 

 number of eggs used in each experiment was so large that we feel justi- 

 fied in drawing certain conclusions from the results. The results of the 

 earlier experiments were somewhat erratic; but taken as a whole, this 

 series leads one to conclude that the chemicals used cannot be depended 

 upon to control the root-knot nematode, because they do not completely 

 inhibit the hatching of the eggs. We do not feel justified in concluding 

 that this is the only reason for the failure of the chemical treatments in 

 the field experiments, because we have not as yet collected sufficient 

 data on the other theories to draw any definite conclusions regarding 

 them. Stone and Smith (6) found that chemicals failed to inhibit the 



