Foott, John H. : J. H. Foott is Farm Advisor Emeritus, San Luis Obispo and Santa Barbara counties

McKenry, Michael V

Phillips, Phil

Striegler, R. K. : R. K. Striegler is Research Scientist, Viticulture and Eizology Research Center, California State University-Fresno

Wolpert Dr, James A.

aged by crows . From these estimates , we calculated a 3 to 4 % loss in production , Berber orchardgrasstested about 40 pounds per acre , for those re - turning the survey . In estimating overall loss , average lossesin the range of 1to as cover crop in commercial 5 % and 6 to 10 % were reported by 28 % and 26 % of the growers , respectively ; vineyard 24 % of the growers indicated losses in the range of 11to 50 % . Control methods used James A . Wolpert P Phil A . Phillips P R . K . Striegler CI John H . Foott V . McKenry Michael Growers were asked to rate the meth - ods used to controlbird pests . Of all of the measures used to frighten or dis - perse birds , shooting was the most com - irrigated during the growing season by mon , followed by gas cannons ( propane Berber orchardgrasscover crop A overhead sprinkler . The total water exploder ) , hawk kites ( kitesthat look reduced thegrowth and yield of ( winter rainfall plus irrigation ) received like predatory birds ) and electronic CabernetSauvignongrapevines . noise makers ( AV - Alarm ) . Shootingand in the control plots was 18.8inches ( 13.0 Some nematode and arthropod gas cannons were rated by 47 % and 40 % plus 5.8 ) in 1988,19.0inches ( 10.4 plus 8.6 ) in 1989 and 17.1inches ( 9.1 plus 8.0 ) pest populations were signifi - of the growers , respectively , as giving in 1990 . The Berber cover plots received slight control ; 25 % and 32 % , respec - cantly lower in the cover crop identical irrigation applications , except tively , said shooting and gas cannonsing , plots ; one was higher . moderately controlled crows . Trapp in 1990when they received 3 inches of netting , recorded bird calls and bird additional irrigation , bringing the total Increasinginterest in the use of cover bombs were also used . Asked how much water received in cover treatments to crops in commercialviticulture they would be willing to spend to re - 20.1 inches . No fertilizerwas applied to prompted a field experiment which the experimental area , except in 1990 duce crow damage in their orchards by demonstrated that a Berber orchardgrass when the Berber plots received 45 50 % , growers gave responses ranging cover crop can severelyreduce grape - pounds of actual nitrogen as UAN - 32 from $ 0 to $ 100 per acre , with an aver - vine growth and yield , alter vine water ( urea and ammonium nitrate . ) age of $ 24.46 per acre . Vines were trained to a two - wire ver - status and influencepest population . Asked to list environmental condi - The recent attention to vineyard tical trellis with wires located at about tions near their orchards that they felt cover crops can be attributed to their 42 inches and 60 inchesabove the soil . contributed to crow problems , growers ability to moderate vine growth under Vines were cordon - trained on the lower commonly listed tall trees and water high fertility conditions , to reduce ero - wire and pruned to a combination of 10 sourcesas contributing to specificbird sion , to improve soil tilth and to aid in - to 12two - bud spurs and four 12 - to 15 - problems . In addition , wooded areas , tegrated pest management goals by bud canes . Canes were wrapped and brushlands and power lineswere associ - harboring beneficial arthropod preda - tied to the upper wire . At the start of the ated with crow problems . tors or parasites . Before cover crop use experiment , vines were considered ex - Conclusion can be recommended , however , the cessivelyvigorous and were yielding competition of cover crops with vines low amounts of poor quality fruit . The Among birds , crowsreportedly cause under various cultural practicesneeds cover crop was being investigated for its the most damage to almonds and other study as does the possibility of potential potential to reduce excessivevine vigor crops throughout Sutter and Yuba coun - encouragement of injurious pests . and thus improve bud fruitfulness and ties . Magpies are the second most detri - vine yield . mental bird speciesreported , closely fol - Trial conditions In one of the three center rows of lowed by blackbirds , starlings and scrub The trial area was a 26.7 - acre , mature , each 12 - rowblock , 10contiguous vines jays . Bird damage is believed to be get - own - rooted Cabernet Sauvignonvine - were selected for uniformity of growth ting worse each year in some orchards , yard located about 8 miles southeast of and were marked as data vines for the as a result of increased bird numbers . Santa Maria in Santa Barbara County . course of the experiment . Data were re - Control methods vary , depending on - The vineyard was planted on a 7 - foot by corded , beginning with the harvest in their cost effectiveness.To reduce dam 12 - footspacing ( vineby row ) . In late 1988and continuing for 2 years . Grape - age by 50 % in their orchards , almond 1987 , Berber orchardgrass was sown inof growers are willing to spend vines were individually hand - harvested , an average the inter - row middles , in four blocks clusterswere counted and per - vine of $ 24.46 per acre , far less than the po - 12middles each ; a 2 - foot strip under the weights recorded . Before harvest , ament tential value of nuts lost to such damage . vines was kept clean with herbicide ap - single 100 - berrysample per treat The most effectivedeterrent appears to plications.Treatmentblocks alternated replicate was taken and weighed to de - be shooting , followed by gas cannons with four 12 - middleblocks of clean cul - termine averageberry weight . The ( propane exploders ) . No control appar - tivation that were maintained by regular sample was crushed and juice was ana - ently gives excellentresults consistently discing and dormant - season herbicide lyzed for sugar concentration ( ' Brix ) , ti - and no improved alternative has been applicationsin a 2 - foot strip under the tratable acidity ( TA ) and pH . During the found . vine rows . Wide plots were designed to subsequent dormant season , vines were restrict , as much as possible , pest migra - pruned and the weight of cane prunings J . Hasey is Farm Advisor , Sutter - Yuba tion from one treatment to another . recorded . counties , and T . P . Salmon is Extension This production area is noted for rela - During the 1990 growing season , Wildlife Specialist , Department of Wildlife tively low winter rainfall and vines are monthly measurements of vine water and Fisheries Biology , UC Davis . CALIFORNIA AGRICULTURE , SEPTEMBER - OCTOBER 1993 23 status , including stomatal conductance and transpiration , were made with a Li - Cor porometer . Leaf water potential was also determined by Arimad pressure bomb . The pressure bomb readings were taken between 0700 and 0900 hours local time and completed before the dissipa - tion of morning coastal fog ; porometer readings were taken at 1200to 1400 hours , about solar noon . Effects seen In 1988 , the first growing season , the Berber cover was becoming established and no effect was seen ( table 1 ) . How - ever , in 1989the cover crop reduced growth of the Cabernet vines by 54 % , and in 1990 it reduced both growth and yield by 58 % and 53 % â?? respectively . In 1990 the effect of Berber cover was still seen , despite the additional 3 inches of irrigation and 45 pounds of actual nitro - gen per acre applied differentially to the Berber plots . Without the supplemental water and fertilizer , vines in the Berber treatment would likely have shown even poorer performance . The effect of the Berber cover crop on vine performance was due , at least partly , to vine water status ( table 2 ) . Vines in the cover crop treatment showed greater water stress ; that is , lower leaf water potential , stomatal con - ductance and transpiration early in the season during the grand period of growth . Later in the season , when water is generally withheld to facilitate ripen - ing , vines in both cover and control plots showed equivalent water status . Pest presence in the vineyard was generally low . However , in 1988 , Willamette mite populations were higher in the disced plots and in 1989 , leahopper and thrips populations were higher in the disced plots whereas cane borers were higher in the Berber plots ( table 3 ) . No effect was seen on the inci - dence of powdery mildew or botrytis bunch rot ( data not shown ) . Increased activity of pocket gophers in the Berber cover plots was noted , but the effect could not be quantified ( data not shown ) . In a study conducted at the Kearney Agricultural Center in 1989 , Berber orchardgrass was found to be an excel - lent nongalling host for root knot nema - todes , Meloidogyize spp . ; M . incognita produced 497 juveniles / gm of root , M . jauaizica produced 177juveniles / gm of M . avenavia yielded 268 juve - root , and niles / gm of root . Berber was a poor host for M . hapla , supporting only 0.4 juveniles / gm of root . 24 CALIFORNIA AGRICULTURE , VOLUME 47 , NUMBER 5 Water status of grapevines was measured in May 1990 . Vine vigor differences are apparent between the clean cultivated plots ( / eft ) and Berber cover plots ( right ) . sufficiently reduced in vigor by the com - Various Meloidogyne spp . were other sites where permanent covers pre - petitive effects of Berber to render them present in the Santa Maria vineyard . vent incorporation of dormant prunings less of a food source for root knot nema - Much of the vineyard was of a finer soil into the soil . tode . Populations of Dagger nematode , texture and not ideally suited for the Cover crops are successfully used in Xiplzinema americaiium , were also signifi - buildup of Meloidogyne populations . Soil coastal vineyards where winter rainfall cantly reduced , having a count of 921250 samples were collected each year of the or irrigation is plentiful and where soils 91 cm3 soil in the non - Berber area and 3 trial , but an extensive sampling was con - are fertile . However , under the cool cli - 250 cm3 in the Berber area . ducted in fall 1990 . A root knot nema - mate and low winter rainfall conditions a tode â?? hot spot â?쳌 was located across of this experiment in the south Central Conclusion sandier portion of two of the Berber rep - Coast , Berber orchardgrass cover crop In conclusion , Berber orchardgrass licates . Samples were collected along the cannot be viewed as a reasonable vine has the potential to greatly reduce the berms adjacent to where Berber had and growth management tool without seri - growth and yield of Cabernet Sauvignon had not been grown . Samples were also ously considering other vineyard fac - and presumably other varieties . How - collected from areas where root knot tors , especially irrigation . ever , reduced growth was not accompa - nematode was not known to occur . nied by an increase in desired vine yield . Findings Reduced growth was expected to im - I . A . Wolpert is Extension Viticulturist , prove light microclimate and , as a result , The first finding was that Meloidogyne Department of Viticulture and Enology , UC improve bud fruitfulness , but this was populations did not become more preva - P.A . Phillips is Area IPM Advisor , Davis ; not the outcome . Deleterious influence lent across the vineyard in spite of the Ventura ; R . K . Striegler is Research Scien - of cover crop on vine growth via nutri - growing of an excellent host , Berber , for tist , Viticulture and Eizology Research Cen - ent competition and allelopathy cannot 3 years down slope from a high ter , California State University - Fresno ; M . be ruled out . Meloidogyne population ( data not pre - V.McKenry is Extension Nematologist , UC Some nematode and arthropod pest sented ) . The second finding was that Riverside and Kearizey Agricultural Center ; populations were significantly lower in vines grown without Berber cover crops 1 . H . Foott is Farm Advisor Emeritus , and the Berber plots . Reduced vine vigor and supported higher populations of San Luis Obispo and Santa Barbara counties . reduced dust accumulation on foliage The authors gratefully acknowledge the Meloidogyne , 347juveniles1250 cm3 soil , may have accounted for the lower ar - support of Bieiz Nacido Vineyards and the whereas vines grown adjacent to Berber thropod populations in the Berber plots . yielded 98 juveniles / 250 cm3 soil . This cooperation of vineyard managers Pete Rich - The appearance of higher cane borer statistically significant finding contra - mond , Kurt Gollnick and Jeff Frey . Partial populations in cover crop treatments dicts the previously mentioned host funding was provided by UCIIPM , Bien after only 2 years is of concern . Further study but supports the notion that vines Nacido Vineyards and Doniaiiie Chandon , investigation grown adjacent to the Berber cover were of this trend is needed in Inc . CALIFORNIA AGRICULTURE , SEPTEMBER - OCTOBER1993 25