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California Agriculture, Vol. 46, No.3

Goat milk found safe from poison oak toxicants
Cover:  Dairy goats may soon receive increased use statewide in biological control of poison oak. Studies underway at UC Davis indicate goats fed poison oak do not produce milk containing the toxicant. Photo by Jack Kelly Clark
May-June 1992
Volume 46, Number 3

Peer-reviewed research and review articles

Initial research indicates dairy goats used to clear poison oak do not transfer toxicant to milk
by Brou Kouakou, David Rampersad, Eloy Rodriguez, Dan L. Brown
| Full text HTML  | PDF  
Researchers report on the first phase of a project to create a low-input biological control for poison oak by browsing goats.
Dairy goats that eat poison oak do not transfer detectible amounts of the toxic principle, urushiol, to the milk or to the urine. Furthermore, this oily, toxic irritant is found in goat manure at less than 9% of its concentration in poison oak leaves. What does all this portend? That farmers using dairy goats to clear poison oak need not worry about contaminating the goats' milk with urushiol. More studies are underway.
Microcomputer program ACRE helps answer: When water is limited, how many acres do you plant?
by Richard L. Snyder
| Full text HTML  | PDF  
Using a new computer program, growers can now develop irrigation regimes that minimize crop damage during periods of drought.
A microcomputer program, ACRE, calculates the number of acres of field and row crops to plant, given a limited water supply. Inputs include crop water balance parameters and the anticipated supply of irrigation water. This program is useful for determining how many acres to plant when the goal is to avoid the kind of water stress that impairs marketable production of a crop.
A greenhouse experiment finds water-sorbing polymers do not conserve water
by John Letey, Pete R. Clark, Christopher Amrhein
| Full text HTML  | PDF  
Polymers do not alter the amount of water plants need; they only alter the storage capacity of soil between irrigations.
To assess claims that water-sorbing polymers promote water conservation, a greenhouse experiment with container-grown marigolds was conducted to determine the effect of adding the polymers to soil mix. Plant growth and water retention in I- and 3-quart containers were not particularly affected, but in the 6-quart size, maximum water retention was significantly higher for the 4 lb/yd3 polymer treatment than for the other treatments, and the time from watering to wilt progressively increased from 6.1 to 7.4 days for the 0, 1, 2 and 4-lb/yd3 treatments. However, no water conservation occurred because evapotranspiration was not significantly affected by the polymer treatment.
Two-year study in San Joaquin County indicates sampling procedures to find nepoviruses in grapevines need improvement
by Deborah A. Golino, Paul Verdegaal, Adib Rowhani, M. Andrew Walker
| Full text HTML  | PDF  
Tests revealed that a high percentage of San Joaquin County vineyards harbored grapevine fan leaf virus; further study of sampling procedures is now underway.
Two debilitating grapevine diseases, fanleaf and yellow vein, are caused by nepoviruses. Once these viruses are established in vineyards along with their nematode vectors, they are extremely difficult to eradicate. Since the use of infected propagating wood can spread the diseases further, the development of rapid diagnostic procedures for these viruses is highly desirable. However, a 2-year study on the identity and incidence of nepovirus-infected grapevines in San Joaquin County vineyards indicates that sampling procedures and ELISA protocols will have to be improved before this virus assay can be used reliably in nursery certification programs.
To anticipate the future, models simulate US. pistachio prices
by Desmond A. Jolly, Kim Norris
| Full text HTML  | PDF  
Since 1979, U.S. pistachio production has grown from 1,000 to 58,000 tons; future grower prices are projected, given alternative market scenarios.
Models developed on U.S. pistachio production simulate grower prices under scenarios of varying import levels and carryover stocks. Grower prices have significantly varied for 13 years, partly because of changes in import levels and domestic production. Bearing acreage has increased dramatically, and as nonbearing acreages mature, substantial growth in production is expected. In 1979, the fledgling U.S. pistachio industry produced 1,000 tons; in 1990, production was more than 58,000 tons. Anticipating future grower prices under alternative market scenarios is of interest, particularly as global political conditions change.
In fumigating Verticillium-infested soils, potassium deficiencies in cotton go down, yields go up
by Bill L. Weir, James E. DeVay, R. Joe Wakeman
| Full text HTML  | PDF  
Soils fumigated with methyl bromide and chloropicrin produced signicantly more lint yield.
Potassium deficiency symptoms occur on Acala SJ-2 cotton when the soils, by test, are not deficient and when other crops grow well without additions of potassium. Field experiments in 1988, 1989 and 1990 resulted in significant lint yield increases when the soils were fumigated with methyl bromide and chloropicrin. Foliar potassium deficiency symptoms were drastically decreased without altering soil potassium levels.
In a study of avocado trees, using less fertilizer more often can reduce nitrate leaching
by Marylynn V. Yates, J. L. Meyer, Mary Lu Arpaia
| Full text HTML  | PDF  
Smaller, more frequent fertilizer applications appeared to minimize the potential for ground water contamination in avocado orchards.
Fertilizing avocado trees in smaller amounts more frequently can reduce nitrate leaching into the soil and thereby decrease contamination of ground wafer.
Normal fruit set is up; shotberries are down: Topical application of ‘Sevillano’ pollen to ‘Manzanillo’ olive proves effective
by G. Steven Sibbett, Mark W. Freeman, Louise Ferguson, Vito S. Polito
| Full text HTML  | PDF  
Topical applications of pollen are a feasible substitute for a pollinizer cultivar.
Topically applied 'Sevillano' olive pollen increased the percentage of normal fruit set and reduced incidence of worthless shotberry 'Manzanillo' olives. Applications were effective up to 90 feet from the pollen source.
Researchers take a look at the versatile Poa annua L.: wanton weed and/or golf turf?
by Lin Wu, James A. Harding, Maurizio Borgonovo, M. Ali Harivandi
| Full text HTML  | PDF  
Identifying the variable characteristics of bluegrass can prove useful in both selective breeding programs and weed management.
Poa annua L. (annual bluegrass) is seen by researchers as both a troublesome' weed, especially on golf courses, and as an attractive turf. A wealth of genetic variations in the morphological, physiological and life history characters of this weedy species has been detected. Awareness of the genetic differences in growth habit and reproductive strategies between annual and perennial biotypes of P. annua can be helpful in managing it as turf, as well as in situations where it is treated as a weed.
By budgeting irrigated pasture growth rates, managers control forage levels and animal performance
by Melvin R. George, Marya E. Robbins, Fremont L. Bell, William J. vanRiet, Gary Markegard, David F. Lile, Charles B. Wilson, Quinton J. Barr
| Full text HTML  | PDF  
Preliminary results are reported from five Northern California pastures where time-controlled grazing was in practice.
Traditionally, little control is exerted over grazing on irrigated pasture. Today, however, with controlled grazing and feed budgeting, the pasture manager can use grazing stock to control forage levels, and forage levels can be used to control animal performance. Pasture budgeting can be applied to California's irrigated pastures when estimates of expected pasture growth are available, according to an ongoing study.
Weed seed in dairy manure depends on collection site
by David W. Cudney, Steven D. Wright, Thomas A. Shultz, John S. Reints
| Full text HTML  | PDF  
Weed seed contamination is greatest in manure from dry cowpens and liquid manure sedimentation handling facilities.
Dairy manure collected for 2 years from various sites in seven Central California dairies was found to contain viable weed seed. Weed seed Contamination Was most Severe when manure was taken from dry COW pens and liquid manure sedimentation handling facilities. Composting did not eliminate all viable weed seed.

Editorial, News, Letters and Science Briefs

California's Long Drought
by Henry J. Vaux
Full text HTML  | PDF  
Webmaster Email: wsuckow@ucanr.edu

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California Agriculture, Vol. 46, No.3

Goat milk found safe from poison oak toxicants
Cover:  Dairy goats may soon receive increased use statewide in biological control of poison oak. Studies underway at UC Davis indicate goats fed poison oak do not produce milk containing the toxicant. Photo by Jack Kelly Clark
May-June 1992
Volume 46, Number 3

Peer-reviewed research and review articles

Initial research indicates dairy goats used to clear poison oak do not transfer toxicant to milk
by Brou Kouakou, David Rampersad, Eloy Rodriguez, Dan L. Brown
| Full text HTML  | PDF  
Researchers report on the first phase of a project to create a low-input biological control for poison oak by browsing goats.
Dairy goats that eat poison oak do not transfer detectible amounts of the toxic principle, urushiol, to the milk or to the urine. Furthermore, this oily, toxic irritant is found in goat manure at less than 9% of its concentration in poison oak leaves. What does all this portend? That farmers using dairy goats to clear poison oak need not worry about contaminating the goats' milk with urushiol. More studies are underway.
Microcomputer program ACRE helps answer: When water is limited, how many acres do you plant?
by Richard L. Snyder
| Full text HTML  | PDF  
Using a new computer program, growers can now develop irrigation regimes that minimize crop damage during periods of drought.
A microcomputer program, ACRE, calculates the number of acres of field and row crops to plant, given a limited water supply. Inputs include crop water balance parameters and the anticipated supply of irrigation water. This program is useful for determining how many acres to plant when the goal is to avoid the kind of water stress that impairs marketable production of a crop.
A greenhouse experiment finds water-sorbing polymers do not conserve water
by John Letey, Pete R. Clark, Christopher Amrhein
| Full text HTML  | PDF  
Polymers do not alter the amount of water plants need; they only alter the storage capacity of soil between irrigations.
To assess claims that water-sorbing polymers promote water conservation, a greenhouse experiment with container-grown marigolds was conducted to determine the effect of adding the polymers to soil mix. Plant growth and water retention in I- and 3-quart containers were not particularly affected, but in the 6-quart size, maximum water retention was significantly higher for the 4 lb/yd3 polymer treatment than for the other treatments, and the time from watering to wilt progressively increased from 6.1 to 7.4 days for the 0, 1, 2 and 4-lb/yd3 treatments. However, no water conservation occurred because evapotranspiration was not significantly affected by the polymer treatment.
Two-year study in San Joaquin County indicates sampling procedures to find nepoviruses in grapevines need improvement
by Deborah A. Golino, Paul Verdegaal, Adib Rowhani, M. Andrew Walker
| Full text HTML  | PDF  
Tests revealed that a high percentage of San Joaquin County vineyards harbored grapevine fan leaf virus; further study of sampling procedures is now underway.
Two debilitating grapevine diseases, fanleaf and yellow vein, are caused by nepoviruses. Once these viruses are established in vineyards along with their nematode vectors, they are extremely difficult to eradicate. Since the use of infected propagating wood can spread the diseases further, the development of rapid diagnostic procedures for these viruses is highly desirable. However, a 2-year study on the identity and incidence of nepovirus-infected grapevines in San Joaquin County vineyards indicates that sampling procedures and ELISA protocols will have to be improved before this virus assay can be used reliably in nursery certification programs.
To anticipate the future, models simulate US. pistachio prices
by Desmond A. Jolly, Kim Norris
| Full text HTML  | PDF  
Since 1979, U.S. pistachio production has grown from 1,000 to 58,000 tons; future grower prices are projected, given alternative market scenarios.
Models developed on U.S. pistachio production simulate grower prices under scenarios of varying import levels and carryover stocks. Grower prices have significantly varied for 13 years, partly because of changes in import levels and domestic production. Bearing acreage has increased dramatically, and as nonbearing acreages mature, substantial growth in production is expected. In 1979, the fledgling U.S. pistachio industry produced 1,000 tons; in 1990, production was more than 58,000 tons. Anticipating future grower prices under alternative market scenarios is of interest, particularly as global political conditions change.
In fumigating Verticillium-infested soils, potassium deficiencies in cotton go down, yields go up
by Bill L. Weir, James E. DeVay, R. Joe Wakeman
| Full text HTML  | PDF  
Soils fumigated with methyl bromide and chloropicrin produced signicantly more lint yield.
Potassium deficiency symptoms occur on Acala SJ-2 cotton when the soils, by test, are not deficient and when other crops grow well without additions of potassium. Field experiments in 1988, 1989 and 1990 resulted in significant lint yield increases when the soils were fumigated with methyl bromide and chloropicrin. Foliar potassium deficiency symptoms were drastically decreased without altering soil potassium levels.
In a study of avocado trees, using less fertilizer more often can reduce nitrate leaching
by Marylynn V. Yates, J. L. Meyer, Mary Lu Arpaia
| Full text HTML  | PDF  
Smaller, more frequent fertilizer applications appeared to minimize the potential for ground water contamination in avocado orchards.
Fertilizing avocado trees in smaller amounts more frequently can reduce nitrate leaching into the soil and thereby decrease contamination of ground wafer.
Normal fruit set is up; shotberries are down: Topical application of ‘Sevillano’ pollen to ‘Manzanillo’ olive proves effective
by G. Steven Sibbett, Mark W. Freeman, Louise Ferguson, Vito S. Polito
| Full text HTML  | PDF  
Topical applications of pollen are a feasible substitute for a pollinizer cultivar.
Topically applied 'Sevillano' olive pollen increased the percentage of normal fruit set and reduced incidence of worthless shotberry 'Manzanillo' olives. Applications were effective up to 90 feet from the pollen source.
Researchers take a look at the versatile Poa annua L.: wanton weed and/or golf turf?
by Lin Wu, James A. Harding, Maurizio Borgonovo, M. Ali Harivandi
| Full text HTML  | PDF  
Identifying the variable characteristics of bluegrass can prove useful in both selective breeding programs and weed management.
Poa annua L. (annual bluegrass) is seen by researchers as both a troublesome' weed, especially on golf courses, and as an attractive turf. A wealth of genetic variations in the morphological, physiological and life history characters of this weedy species has been detected. Awareness of the genetic differences in growth habit and reproductive strategies between annual and perennial biotypes of P. annua can be helpful in managing it as turf, as well as in situations where it is treated as a weed.
By budgeting irrigated pasture growth rates, managers control forage levels and animal performance
by Melvin R. George, Marya E. Robbins, Fremont L. Bell, William J. vanRiet, Gary Markegard, David F. Lile, Charles B. Wilson, Quinton J. Barr
| Full text HTML  | PDF  
Preliminary results are reported from five Northern California pastures where time-controlled grazing was in practice.
Traditionally, little control is exerted over grazing on irrigated pasture. Today, however, with controlled grazing and feed budgeting, the pasture manager can use grazing stock to control forage levels, and forage levels can be used to control animal performance. Pasture budgeting can be applied to California's irrigated pastures when estimates of expected pasture growth are available, according to an ongoing study.
Weed seed in dairy manure depends on collection site
by David W. Cudney, Steven D. Wright, Thomas A. Shultz, John S. Reints
| Full text HTML  | PDF  
Weed seed contamination is greatest in manure from dry cowpens and liquid manure sedimentation handling facilities.
Dairy manure collected for 2 years from various sites in seven Central California dairies was found to contain viable weed seed. Weed seed Contamination Was most Severe when manure was taken from dry COW pens and liquid manure sedimentation handling facilities. Composting did not eliminate all viable weed seed.

Editorial, News, Letters and Science Briefs

California's Long Drought
by Henry J. Vaux
Full text HTML  | PDF  

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