(D.;».*W 



CHAPTER X 



OBSTRUCTIONS TO GROWTH AND 

 DEVELOPMENT 



The obstrucftions to growth may be treated under 

 the following heads: 



1 . Seaso7t and Climate. 



2. Weeds. 



3. Diseases due to parasitic fimgi and bacteria. 



4. Insects. 



5 . A rsen ica I poison ing . 



I. Influence of Season and Climate. — The in- 

 jurious influence of dry weather at planting-time has 

 alread}^ been observed ("Viability," page 66). At 

 the (Hatch)' Massachusetts Experiment Station it was 

 observed that the wet condition of the soil at the time 

 of planting appeared to induce the rotting of the 3'oung 

 plants just below ground. The occurrence of several 

 extremely hot sunny daj-s in July, following a long 

 rainy period, caused the plants to wilt from the wet 

 condition of the soil and low vitality. No disease was 

 apparent. Probably these plants showed the injurious 

 results consequent on defective respiration due to high 

 temperatures. Frost may cut down early planted 

 potatoes. 



Tip Burn."^ — This is most common in Northeastern 



• Mass. (Hatch) Report, 1898, p. 52. 



5" Ver. RepKjrt, 1899, p 151; Bui. 72, p. 10. (N. Y.) Cornell Bui. 113, p. 309. 

 Conn. RejKirt iS (1894), p. 133. 



Ill 



