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California Agriculture, Vol. 51, No.1

Flood damage estimates rise
Cover:  In southern Sacramento County, a private levee burst and allowed the Mokelumne River to flood this vineyard. January flood damge to winegrapes statewide was estimated at $13.8 million by the California Department of Food and Agriculture... Photo by Jack Kelly Clark
January-February 1997
Volume 51, Number 1

Peer-reviewed research and review articles

Post-fire herbicide sprays enhance native plant diversity
by Joseph M. DiTomaso, Evelyn A. Healy, Daniel B. Marcum, Guy B. Kyser, Michelle S. Rasmussen
| Full text HTML  | PDF  
Using herbicides to reduce competition from shrubs and forbs reduces mortality of conifers.
Following catastrophic fire, broad-spectrum herbicides such as hexazinone are often used to control shrubs and forbs that compete with planted conifers. This practice encourages rapid growth and reduces mortality of conifers. Although the initial effect is to reduce native plant species richness, recovery is rapid and plant diversity exceeds that in untreated areas within 8 years of application. Success of native forb and grass species in herbicide-treated areas appears to be due to early suppression of otherwise dominant shrubs.
Apple russetting influenced by more than copper sprays
by Beth L. Teviotdale, Mario Viveros, Joseph A. Grant
| Full text HTML  | PDF  
Russetting of apples was unpredictable and sporadic regardless of timing of copper sprays.
Apple trees are commonly treated with antibiotics during bloom and early shoot growth to control fire-blight, but antibiotic resistance is a concern. To prevent antibiotic resistance, copper treatments may be beneficial, but would be feasible only if stages in bloom or fruit development could be identified that are not subject to fruit russetting. Most fruit russetting results from injury to epidermal cells early in fruit development. Studies in Kern and San Joaquin counties showed copper-induced russetting of apple fruit was unpredictable and sporadic regardless of application timing. Severity of damage varied from year to year.
Cover crops can increase lettuce drop
by Steven T. Koike, Richard F. Smith, Louise E. Jackson, Lisa J. Wyland, William E. Chaney, John I. Inman
| Full text HTML  | PDF  
Phacelia, lana woollypod vetch and Austrian winter pea cover crops were associated with higher lettuce drop incidence.
Although cover crops contribute many benefits to organic and conventional agricultural systems, they may play a significant role in the epidemiology of soil-borne diseases. A 2-year study shows that Sclerotinia minor, which causes lettuce drop disease, is a pathogen of phacelia, lana woollypod vetch and Austrian winter pea cover crops. Greenhouse and field inoculations failed to result in S. minor infections of oilseed radish, barley and fava bean cover crops. It appears these three cover crops can be safely incorporated into lettuce rotations without increasing the occurrence of lettuce drop.
Sulfur can suppress mite predators in vineyards
by Rachid Hanna, Frank G. Zalom, Lloyd T. Wilson, George M. Leavitt
| Full text HTML  | PDF  
Sulfur applications for powdery mildew control can exacerbate spider mite problems.
The Pacific spider mite and the Willamette spider mite are the most common mite pests on grapevines. A single-season study of a vineyard near Madera showed that regular sulfur applications for powdery mildew control can exacerbate spider mite problems in vineyards by suppressing populations of predatory thrips and predatory mites.
Africanized bees, 1990–1995: Initial rapid invasion has slowed in the U.S.
by P. Kirk Visscher, Richard S. Vetter, F. Chris Baptista
| Full text HTML  | PDF  
Africanized honey bee&s impact on California will depend on beekeeping practices and management of the bee as an urban pest.
Africanized honey bees (AHB) can seriously disrupt beekeeping and agricultural practices, as well as kill people. This study examines the progress of AHB in the United States from their first detection in 1990 through 1995. AHB are now established in southern portions of Texas, New Mexico, Arizona and California. While the bees' northward migration has slowed dramatically in recent years, the ultimate extent of their range remains uncertain. AHB's impact on California agriculture will depend on how much of the state they colonize, and on the effectiveness of new beekeeping practices and management of AHB as an urban pest.
Oaks grown from nursery stock have better survival rate
by Theodore E. Adams, Peter B. Sands, Marion E. Stanley
| Full text HTML  | PDF  
Transplanted blue oak nursery stock has a survival advantage over seedlings developing from directly planted acorns.
Studies comparing the performance of blue and valley oak seedlings developing from directly planted acorns and 2-to-3-month-old nursery stock were conducted at several locations in California. Results suggest that transplanted blue oak nursery stock has a survival advantage over seedlings developing from directly planted acorns when the plant materials are grown together under the same conditions. However, the greater cost of nursery stock may make this plant material unattractive for restoration.
Workers prefer growers over FLCs
by Gregory Encina Billikopf
| Full text HTML  | PDF  
Workers perceive growers as providing more work and better pay, benefits and working conditions.
Given a choice, crew workers overwhelmingly prefer working for a grower rather than for a farm labor contractor. FLCs generally have a couple of advantages over growers including less of a language barrier and the potential for providing longer work seasons. Nevertheless, workers perceive growers as providing more work (per day and per season); better pay, benefits and working conditions; better treatment; and even better communication and instructions.
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California Agriculture, Vol. 51, No.1

Flood damage estimates rise
Cover:  In southern Sacramento County, a private levee burst and allowed the Mokelumne River to flood this vineyard. January flood damge to winegrapes statewide was estimated at $13.8 million by the California Department of Food and Agriculture... Photo by Jack Kelly Clark
January-February 1997
Volume 51, Number 1

Peer-reviewed research and review articles

Post-fire herbicide sprays enhance native plant diversity
by Joseph M. DiTomaso, Evelyn A. Healy, Daniel B. Marcum, Guy B. Kyser, Michelle S. Rasmussen
| Full text HTML  | PDF  
Using herbicides to reduce competition from shrubs and forbs reduces mortality of conifers.
Following catastrophic fire, broad-spectrum herbicides such as hexazinone are often used to control shrubs and forbs that compete with planted conifers. This practice encourages rapid growth and reduces mortality of conifers. Although the initial effect is to reduce native plant species richness, recovery is rapid and plant diversity exceeds that in untreated areas within 8 years of application. Success of native forb and grass species in herbicide-treated areas appears to be due to early suppression of otherwise dominant shrubs.
Apple russetting influenced by more than copper sprays
by Beth L. Teviotdale, Mario Viveros, Joseph A. Grant
| Full text HTML  | PDF  
Russetting of apples was unpredictable and sporadic regardless of timing of copper sprays.
Apple trees are commonly treated with antibiotics during bloom and early shoot growth to control fire-blight, but antibiotic resistance is a concern. To prevent antibiotic resistance, copper treatments may be beneficial, but would be feasible only if stages in bloom or fruit development could be identified that are not subject to fruit russetting. Most fruit russetting results from injury to epidermal cells early in fruit development. Studies in Kern and San Joaquin counties showed copper-induced russetting of apple fruit was unpredictable and sporadic regardless of application timing. Severity of damage varied from year to year.
Cover crops can increase lettuce drop
by Steven T. Koike, Richard F. Smith, Louise E. Jackson, Lisa J. Wyland, William E. Chaney, John I. Inman
| Full text HTML  | PDF  
Phacelia, lana woollypod vetch and Austrian winter pea cover crops were associated with higher lettuce drop incidence.
Although cover crops contribute many benefits to organic and conventional agricultural systems, they may play a significant role in the epidemiology of soil-borne diseases. A 2-year study shows that Sclerotinia minor, which causes lettuce drop disease, is a pathogen of phacelia, lana woollypod vetch and Austrian winter pea cover crops. Greenhouse and field inoculations failed to result in S. minor infections of oilseed radish, barley and fava bean cover crops. It appears these three cover crops can be safely incorporated into lettuce rotations without increasing the occurrence of lettuce drop.
Sulfur can suppress mite predators in vineyards
by Rachid Hanna, Frank G. Zalom, Lloyd T. Wilson, George M. Leavitt
| Full text HTML  | PDF  
Sulfur applications for powdery mildew control can exacerbate spider mite problems.
The Pacific spider mite and the Willamette spider mite are the most common mite pests on grapevines. A single-season study of a vineyard near Madera showed that regular sulfur applications for powdery mildew control can exacerbate spider mite problems in vineyards by suppressing populations of predatory thrips and predatory mites.
Africanized bees, 1990–1995: Initial rapid invasion has slowed in the U.S.
by P. Kirk Visscher, Richard S. Vetter, F. Chris Baptista
| Full text HTML  | PDF  
Africanized honey bee&s impact on California will depend on beekeeping practices and management of the bee as an urban pest.
Africanized honey bees (AHB) can seriously disrupt beekeeping and agricultural practices, as well as kill people. This study examines the progress of AHB in the United States from their first detection in 1990 through 1995. AHB are now established in southern portions of Texas, New Mexico, Arizona and California. While the bees' northward migration has slowed dramatically in recent years, the ultimate extent of their range remains uncertain. AHB's impact on California agriculture will depend on how much of the state they colonize, and on the effectiveness of new beekeeping practices and management of AHB as an urban pest.
Oaks grown from nursery stock have better survival rate
by Theodore E. Adams, Peter B. Sands, Marion E. Stanley
| Full text HTML  | PDF  
Transplanted blue oak nursery stock has a survival advantage over seedlings developing from directly planted acorns.
Studies comparing the performance of blue and valley oak seedlings developing from directly planted acorns and 2-to-3-month-old nursery stock were conducted at several locations in California. Results suggest that transplanted blue oak nursery stock has a survival advantage over seedlings developing from directly planted acorns when the plant materials are grown together under the same conditions. However, the greater cost of nursery stock may make this plant material unattractive for restoration.
Workers prefer growers over FLCs
by Gregory Encina Billikopf
| Full text HTML  | PDF  
Workers perceive growers as providing more work and better pay, benefits and working conditions.
Given a choice, crew workers overwhelmingly prefer working for a grower rather than for a farm labor contractor. FLCs generally have a couple of advantages over growers including less of a language barrier and the potential for providing longer work seasons. Nevertheless, workers perceive growers as providing more work (per day and per season); better pay, benefits and working conditions; better treatment; and even better communication and instructions.

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