Plant Growth Regulation 



Increased potential for practical control of plant 

 growth and development with both naturally oc- 

 curring and synthetic growth-regulation sub- 

 stances has been achieved through discovery and 

 evaluation of new chemical substances and deter- 

 mination of their mechanism of action. Applica- 

 tion of such technology is having significant im- 

 pact on production practices, harvesting, and cur- 

 ing of tobacco, and has created new potential uses 

 for tobacco as a food. 



Cutler, H. G., and T. P. Gaines. 1971. Some preliminary ob- 

 servations on greenhouse-grown tobacco treated with 2-chlo- 

 roethylphosphoric acid al varying Ph's. Tobacco Science 171: 

 43-45. 



Dropkin. V. H.. J. P. Helgeson. and C. P. Upper. 1969. Hy- 

 persensitivity reaction of tomatoes resistant to Meloidgyne 

 Incognita: Reversal by cytokinins. J. Nematology l:5-'5-61. 



King, E. E. 1973. Endopolymethylgalacturonase of boll weevil 

 larvae: An initiator of cotton flower bud abscission. J. Insect 

 Physiol. 19:2433-2437. 



Miles, J. D., G. L. StelTens, T. T. Gaines, and M. G. Stephen- 

 son. 1972. Flue-cured tobacco "yellowed" with an ethylene 

 releasing agent prior to harvest. Tobacco Science 16:71-74. 



Mitchell, J. W. and Luis E. Gregory. 1972. Enhancement of 

 overall plant growth, a new response to brassins. Nature: New 

 Biology 239:253-254. 



Mitchell, J. W., N. Mandava, J. F. Worley, J. R. Plimmer, 

 and M. V. Smith. 1970. Brassins — A new family of plant hor- 

 mones from rape pollen. Nature 225:1065-1066. 



Tso, T C and G. B. Gori. 1976. A new approach in tobacco 

 production as food source and smoke material — Year 1976 and 

 Year 2000, Proc, 6th International Tobacco Science Congress, 

 Tokyo, Japan, (in press). 



Wells, J. M., R. G. Cutler, and R. J. Cole. 1976. Toxicity and 

 plant growth regulator effects of cytochalasin H isolated from 

 Phomopsis sp. Microbiol, 22:1137-1143. 



Biological Control of Insects 



Advances in the past decade in the discovery, 

 identification, and synthesis in vitro of sex-stimu- 

 lating and food-locating chemicals opens the pos- 

 sibility of disrupting one or more vital processes 

 in insects in locating specific food plants and in 

 aggregating on susceptible plants. These advances 

 provide an important new tool that permits man to 

 manage insect populations onto sites or into situa- 

 tions where they can be destroyed or fail to fulfill 

 a vital stage in their life history. 



Studies of insect hormone systems have led to 

 potential methods of disrupting growth and matu- 

 ration of insects in nature by the application of 

 small amounts of synthetic hormones. Hormones 

 that disrupt the synthesis and breakdown of chitin 

 in the insect cuticle are finding application both in 

 agriculture and in controlling insects that attack 



man. The characterization of indigenous patho- 

 gens of insects has provided better understanding 

 of the mortality factors influencing insect popula- 

 tions. Two classes of pathogens, bacteria and vi- 

 ruses, are now commercially produced for insect 

 control in agriculture, forestry, and urban envi- 

 ronments. The pathogens do not interfere with, 

 but augment other biological control methods. 

 Studies on insect genetics have resulted in the 

 potential use of the hybrid sterility principle 

 where the mating of a harmless species with a 

 pest like the tobacco budworm results in sterile 

 male offspring. 



Dulmage, H. T. 1970. Insecticidal activity of HD-1, a new iso- 

 late of Bacillus thuringiensis var. alesti. J. Invertebr. Pathol. 

 15:232-239. 



Hawks, R. B. and A. Mayfield 1976. Host specificity and biol- 

 ogy studies of Coleophora purthenica Meyrick (Lepidoptera: 

 Coleophosidae), an insect for the biological control of Rus- 

 sian thistle. Univ. of Idaho. Dept. Entomol., Anniversary Pub- 

 lication No. 6:37-43. 



Hodgson, J. M., and N. E. Rees. 1976. Dispersal of Rhinocyl- 

 lus Conicus for biological control of Musk thistle. Weed Sci- 

 ence 24:. 59-62. 



Maddox, D. M., L. A. Andres, R. D. Hennessay, R. D. Black- 

 burn, and N. R. Spencer. 1971. Insects to control alligator 

 weed, an invader of aquatic ecosystems in the U.S. Bio- 

 Science 21:985-993. 



Petersen, J. V., H. C. Chapman, and D. B. Woodward. 1967. 

 Nematode of Aedes Solicitans (Walker) in Louisiana. Mosqui- 

 to News. 27:493-498. 



Peterson, J. V. and O. R. Willis. 1972. Procedures for the 

 Mass Rearing of a Mermithid Parasite of Mosquitoes. 

 Mosquito News. 32:226-230. 



Proshold, P. I. and L. E. LaChance. 1974. Analysis of sterility 

 in hybrids from interspecific crosses between Heliothis vires- 

 censiind H. subflexa. Ann. Entomol. Soc. Amer. 67:445-449. 



Roelofs, W. L. 1967. Sex attractanis for insect control. Health 

 News 44:409. 



Roelofs, W. L. and A. Comeau. 1968. Sex pheromone percep- 

 tion. Nature 220:600-601. 



Summers, M. 1975 Baculoviruses for insect pest control: 

 safety considerations. Amer. Soc. Microbiology, Washington, 

 D. C. 188 pp. 



Plant Virology 



Techniques to isolate and identify viroids re- 

 sulted in special gel electrophoresis and sedimen- 

 tation techniques now universally utilized. Using 

 these techniques, it was conclusively demonstrat- 

 ed that infectious RNA (viroids) has a low mole- 

 cular weight and that viroids therefore difl'er 

 basically from conventional viruses. Development 

 and improvements in freeze-etch and related tech- 

 niques have made electron microscope assays of 

 biological specimens so rapid the medical sci- 



AORICULTURE 1 1 



