California Agriculture
California Agriculture
California Agriculture
University of California
California Agriculture

Archive

October 1977
Volume 31, Number 10

Peer-reviewed research and review articles

Hydrilla, a new noxious aquatic weed in California
by Richard R. Yeo, W. B. McHenry
| Full text HTML  | PDF  
Citizens are asked to help identify possible growths of an aggressive new foreign plant recently introduced to California, and already widespread in Florida's waterways.
Abstract Not Available – First paragraph follows: Since about 1776 California has been continually plagued by the inadvertent introduction of foreign plants that spread rapidly and become weeds. Examples include crabgrass (both smooth and hairy), yellow starthistle, oxalis, bermudagrass, and johnsongrass.
Vineyard management and nematode populations
by Howard Ferris, Michael V. McKenry
| Full text HTML  | PDF  
In studies conducted in 1973-76, the greatest concentrations of nema-todes were found to be associated with feeder roots. To be efficient, nematode treatment must be applied to the feeder-root area, and must also be considered in conjunction with alleviating other stresses on the vine.
Abstract Not Available – First paragraph follows: Many factors in soil interact to reduce the effectiveness of grapevine roots, compounding the debilitating effects of nematodes on grapevines. Since optimum grape production requires a healthy, vigorous root system, these factors must be considered in vineyard management.
Biological control: Pitting insects against insects
by Robert M. Boardman
| Full text HTML  | PDF  
UC scientists have achieved major successes in controlling pest insects and weeds by use of the pests natural enemies.
Abstract Not Available – First paragraph follows: Biological control involves discovering, importing, and using the most effective natural enemies of pest insects or weeds that can be found. More than 10 million natural enemies of many kinds are released each year by the University of California (UC) through its Biological Control divisions at Albany and Riverside.
Pesticide applications can be reduced by forecasting the occurrence of fireblight bacteria
by Sherman V. Thomson, Milton N. Schroth, William J. Moller, Wilbur O. Reil, James A. Beutel, Clarence S. Davis
| Full text HTML  | PDF  
Fireblight bacteria have been isolated from pear flowers on a selective medium and their occurrence has been correlated with weather. By averaging daily maximum and minimum temperatures, pear growers can now more accurately predict the presence of fireblight bacteria and apply pesticide sprays only as necessary.
Abstract Not Available – First paragraph follows: Fireblight, caused by the bacterium Erwinio amylovora, is an erratic and devastating disease of pear orchards. Native to North America, it was first observed in California in the 1890s after slowly crossing the continent from the east, decimating pear orchards in its path. Fireblight has the potential to destroy an established orchard in one season if uncontrolled. With 37,440 acres of hearing trees producing a crop of 353,500 tons valued at $44 million, California pear producers have traditionally spared little in their protection efforts to keep the disease in check.
Walnut varieties differ in susceptibility to codling moth damage
by William H. Olson
| Full text HTML  | PDF  
In a trial of ten walnut varieties, initiated in 1974 and repeated in 1975 and 1976, Ashley and Chico varieties were the most susceptible to first-brood codling moth damage and, along with Vina and Serr (all early varieties), the most susceptible to second-brood damage. Mid-season and late-season varieties had considerably less damage.
Abstract Not Available – First paragraph follows: Coding moth, Laspeyresia pomonella (Linn), is one of the most serious pests attacking walnuts, Yet many growers and researchers have observed that certain walnut varieties are more susceptible to coding moth damage than others.
Jojoba wax extraction and bleaching
by Demetrios M. Yermanos, Gurcharan Dhillon, Ronald Holmes
| Full text HTML  | PDF  
Jojoba yielded 33 percent wax extracted by mechanical pressure and 48 percent extracted by solvent. Color and odor can be removed by filtration.
Abstract Not Available – First paragraph follows: The quantities of jojoba seed available at present for extraction are too small to be handled by existing commercial oil seed processing plants, most of which have capacities exceeding 50 tons of seed per day. Instead, small mechanical presses or solvent extractors are being used. Following is a summary of experience we have gained on jojoba wax extraction to date.
Controlling powdery mildew in field roses
by Albert O. Paulus, Jerry Nelson, Otis Harvey
| Full text HTML  | PDF  
Ciba Geigy 105, Bayleton, Rohm-Haas 2161, Funginex, and Dupont 4423 are new fungicides which show promise for the control of rose powdery mildew.
Abstract Not Available – First paragraph follows: Powdery mildew of rose, caused by the fungus Sphaerotheca pannosa, results in unsightly and frequently malformed leaves and flowers, and may reduce growth. Several new fungicides were evaluated for the control of powdery mildew in southern California commercial rose fields.
Beet free periods—the key to higher sugar beet yields
by James E. Duffus
| Full text HTML  | PDF  
Keeping aphid-transmitted yellowing virus diseases in check by use of beet free periods, cleanup of weed beets, and use of tolerant varieties raised sugar production 0.86 tons per acre for 1970 to 1975 compared to the period 1950 to 1967.
Abstract Not Available – First paragraph follows: The sugar beet, a product of research, has been confronted with crisis after crisis in its role as a supplier of one of the cheapest and purest of foods. One of the most recent maladies to take heavy tolls in the production of this crop has been the aphid-transmitted yellowing virus diseases.

News and Opinion

Guilt by association
by J. B. Kendrick
Full text HTML  | PDF  
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October 1977
Volume 31, Number 10

Peer-reviewed research and review articles

Hydrilla, a new noxious aquatic weed in California
by Richard R. Yeo, W. B. McHenry
| Full text HTML  | PDF  
Citizens are asked to help identify possible growths of an aggressive new foreign plant recently introduced to California, and already widespread in Florida's waterways.
Abstract Not Available – First paragraph follows: Since about 1776 California has been continually plagued by the inadvertent introduction of foreign plants that spread rapidly and become weeds. Examples include crabgrass (both smooth and hairy), yellow starthistle, oxalis, bermudagrass, and johnsongrass.
Vineyard management and nematode populations
by Howard Ferris, Michael V. McKenry
| Full text HTML  | PDF  
In studies conducted in 1973-76, the greatest concentrations of nema-todes were found to be associated with feeder roots. To be efficient, nematode treatment must be applied to the feeder-root area, and must also be considered in conjunction with alleviating other stresses on the vine.
Abstract Not Available – First paragraph follows: Many factors in soil interact to reduce the effectiveness of grapevine roots, compounding the debilitating effects of nematodes on grapevines. Since optimum grape production requires a healthy, vigorous root system, these factors must be considered in vineyard management.
Biological control: Pitting insects against insects
by Robert M. Boardman
| Full text HTML  | PDF  
UC scientists have achieved major successes in controlling pest insects and weeds by use of the pests natural enemies.
Abstract Not Available – First paragraph follows: Biological control involves discovering, importing, and using the most effective natural enemies of pest insects or weeds that can be found. More than 10 million natural enemies of many kinds are released each year by the University of California (UC) through its Biological Control divisions at Albany and Riverside.
Pesticide applications can be reduced by forecasting the occurrence of fireblight bacteria
by Sherman V. Thomson, Milton N. Schroth, William J. Moller, Wilbur O. Reil, James A. Beutel, Clarence S. Davis
| Full text HTML  | PDF  
Fireblight bacteria have been isolated from pear flowers on a selective medium and their occurrence has been correlated with weather. By averaging daily maximum and minimum temperatures, pear growers can now more accurately predict the presence of fireblight bacteria and apply pesticide sprays only as necessary.
Abstract Not Available – First paragraph follows: Fireblight, caused by the bacterium Erwinio amylovora, is an erratic and devastating disease of pear orchards. Native to North America, it was first observed in California in the 1890s after slowly crossing the continent from the east, decimating pear orchards in its path. Fireblight has the potential to destroy an established orchard in one season if uncontrolled. With 37,440 acres of hearing trees producing a crop of 353,500 tons valued at $44 million, California pear producers have traditionally spared little in their protection efforts to keep the disease in check.
Walnut varieties differ in susceptibility to codling moth damage
by William H. Olson
| Full text HTML  | PDF  
In a trial of ten walnut varieties, initiated in 1974 and repeated in 1975 and 1976, Ashley and Chico varieties were the most susceptible to first-brood codling moth damage and, along with Vina and Serr (all early varieties), the most susceptible to second-brood damage. Mid-season and late-season varieties had considerably less damage.
Abstract Not Available – First paragraph follows: Coding moth, Laspeyresia pomonella (Linn), is one of the most serious pests attacking walnuts, Yet many growers and researchers have observed that certain walnut varieties are more susceptible to coding moth damage than others.
Jojoba wax extraction and bleaching
by Demetrios M. Yermanos, Gurcharan Dhillon, Ronald Holmes
| Full text HTML  | PDF  
Jojoba yielded 33 percent wax extracted by mechanical pressure and 48 percent extracted by solvent. Color and odor can be removed by filtration.
Abstract Not Available – First paragraph follows: The quantities of jojoba seed available at present for extraction are too small to be handled by existing commercial oil seed processing plants, most of which have capacities exceeding 50 tons of seed per day. Instead, small mechanical presses or solvent extractors are being used. Following is a summary of experience we have gained on jojoba wax extraction to date.
Controlling powdery mildew in field roses
by Albert O. Paulus, Jerry Nelson, Otis Harvey
| Full text HTML  | PDF  
Ciba Geigy 105, Bayleton, Rohm-Haas 2161, Funginex, and Dupont 4423 are new fungicides which show promise for the control of rose powdery mildew.
Abstract Not Available – First paragraph follows: Powdery mildew of rose, caused by the fungus Sphaerotheca pannosa, results in unsightly and frequently malformed leaves and flowers, and may reduce growth. Several new fungicides were evaluated for the control of powdery mildew in southern California commercial rose fields.
Beet free periods—the key to higher sugar beet yields
by James E. Duffus
| Full text HTML  | PDF  
Keeping aphid-transmitted yellowing virus diseases in check by use of beet free periods, cleanup of weed beets, and use of tolerant varieties raised sugar production 0.86 tons per acre for 1970 to 1975 compared to the period 1950 to 1967.
Abstract Not Available – First paragraph follows: The sugar beet, a product of research, has been confronted with crisis after crisis in its role as a supplier of one of the cheapest and purest of foods. One of the most recent maladies to take heavy tolls in the production of this crop has been the aphid-transmitted yellowing virus diseases.

News and Opinion

Guilt by association
by J. B. Kendrick
Full text HTML  | PDF  

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