8 



Properties of Herbicides Influencing Their Physiological 

 Effectiveness in Weed Control . (1) Measure physical and chemical 

 properties of herbicides that influence their effectiveness in weed 

 control and evaluate these properties in plants. (2) Study reactions 

 of herbicides and interaction with factors of environment as they 

 influence herbicidal effectiveness. (3) Evaluate problem of form- 

 ulation of herbicides in relation to their effectiveness, (h) Eval- 

 uate molecular modifications as a factor in herbicide activity. 



Agr. Chem.. 3U9 (W-ll) Coop. USDA 



Influence of Environmental Factors on the Effectiveness of 

 Herbicides . To determine (1) influence of soil moisture on effec- 

 tiveness of 2,k-D, CHU, etc. as pre-emergence herbicides on corn; 

 (2) influence of soil organic matter, porosity, and fertilizer level 

 on effectiveness of 2,k-D as pre-emergence herbicide on corn; (3) 

 influence of moisture, competition, light, and temperatures on 2,U-D 

 injury and weed control; (U) influence of nutrient concentration, 

 N, and K balance on 2,U-D injury in greenhouse; and (5) physiological, 

 morphological and other changes in plants where injury has been 

 induced by above treatments. 



Agron., Bot., Engin., PI. Path. 1229 (NE-12) 



Microbiological Studies in Weed Control . Learn reciprocal re- 

 lationships of various weed and brush control chemicals and soil 

 microorganisms. 



Bact. 13U6-C 



Virus Diseases of Weeds . To determine (1) identity of viruses 

 attacking weeds in Puerto Rico; (2) means of propagation of viruses 

 of weeds; and (3) in cases where transmission of virus is by insect 

 vectors, to identify insect vectors and relation between vectors 

 and viruses; (U) host range of weed viruses in order to determine 

 if plants of economic value are susceptible; and (5) control methods 

 if plants of economic value are affected by weed viruses. 



PI. Path. 63 



Use of Growth Regulating Substances for Weed Control . To in- 

 vestigate and evaluate possibilities of new herbicides for selective 

 control of annual and perennial weeds and grasses. 



Bot., Agr. Engin. 100 



Movement and Persistence of Herbicides in the Soil . To deter- 

 mine (1) persistence of certain herbicides in soil; (2) lateral 

 diffusion of certain herbicides in soil; and (3) how these proper- 

 ties vary with changes in soil moisture, temperature or soil type. 



Agron. h$ (S-18) 



Effect of Certain Insecticides and Herbicides upon the Bio- 

 chemical Activities of the Soil and upon Plant Growth . (1) Estab- 

 lish safe limits of concentration of newer types of insecticides 

 that may be incorporated into the soil without adversely affecting 

 microbiological activities in the soil. (2) Learn lethal con- 

 centration of insecticides for plant growth; and (3) duration of 

 possible injurious effects from overdosages. 



Agron. %. 



