Selection of Sampling Methods to Determine Weed Abundance in Apple (<i>Malus domestica</i>) Orchards

Conn, Jeffery S.; Proctor, Charles H.; Skroch, W. A.

doi:10.1017/s0043174500026126

Cited by 7 publications

(5 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The search for optimal strategies that are cost effective in specific circumstances has been improved by the optimal use of prior information. This gave rise to devices like stratified, cluster, systematic and sequential sampling, which can be combined and specialized in many ways ( Conn et al ., 1982 ).…”

Section: Introductionmentioning

confidence: 99%

Evaluating field‐scale sampling methods for the estimation of mean plant densities of weeds

2000

View full text Add to dashboard Cite

The 1 weed¯ora (comprising seven species) of a ®eld continuously grown with soyabean was simulated for 4 years, using semivariograms established from previous ®eld observations. Various sampling methods were applied and compared for accurately estimating mean plant densities, for diering weed species and years. The tested methods were based on (a) random selection wherein samples were chosen either entirely randomly, randomly with at least 10 or 20 m between samples, or randomly after stratifying the ®eld; (b) systematic selection where samples were placed along diagonals or along zig-zagged lines across the ®eld; (c) predicted Setaria viridis (L.) P. Beauv seedling maps which were used to divide the ®eld into low-and highdensity areas and to choose the largest sample proportion in the high-density area. For each method, sampling was performed with 5±40 samples. Systematic methods generally resulted in the lowest estimation error, followed by the random methods and ®nally by the predicted-map methods. In case of species over-or under-represented along the diagonals or the zig-zag sampling line, the systematic methods performed badly, especially with low sample numbers. In those instances, random methods were best, especially those imposing a minimal distance between samples. Even for S. viridis, the methods based on predicted S. viridis maps were not satisfactory, except with low sample numbers. The relationships between sampling error and species characteristics (mean density, variability, spatial structures) were also studied.In previous work (Colbach et al., 2000), the seedling densities of seven weed species [Amaranthus retro¯exus L.; Asclepias syriaca L.; Chenopodium album L.; Cirsium arvense (L). Scop.; Elytrigia repens (L.) Nevski; Setaria viridis (L.) P. Beauv.; Sinapis arvensis L.] were counted in a continuously grown soyabean [Glycine max (L.) Merr.] ®eld (244 m´54 m) at the Swan Lake Research Farm, Stevens Co., Minnesota, USA. From 1993 to 1997, the densities of the seven weed species were counted on 0.1-m 2 quadrats at 410 permanently marked locations within a 6.1-m (20-foot) grid system. The ®eld received standard weed management practices, which 412 N Colbach et al.

show abstract

Section: Introductionmentioning

confidence: 99%

Evaluating field‐scale sampling methods for the estimation of mean plant densities of weeds

2000

View full text Add to dashboard Cite

show abstract

“…In July 1982, we counted the number of mullein plants > 30 cm high in a strip 10 m wide around the edges of the study sites and in one-third of the tree rows, and the number of C. verbasci on the plants. This method ignored plants > 10 m from the sites, so in July 1983 we counted all the mullein plants seen when walking for 10 min in each orchard (Conn et al 1982), including those up to ca. 100 m away.…”

Section: Methodsmentioning

confidence: 99%

SEASONAL ABUNDANCE OF THE MULLEIN BUG, CAMPYLOMMA VERBASCI (MEYER) (HETEROPTERA: MIRIDAE), ON APPLE AND MULLEIN IN THE OKANAGAN VALLEY

1990

View full text Add to dashboard Cite

The mullein bug, Campylomma verbasci (Meyer) (Heteroptera: Miridae), was studied in and around 17 apple orchards in the Okanagan Valley during 1982–1984. Apple and pear were overwintering hosts and the principal perennial hosts during summer months. Campylomma verbasci was the most abundant mirid on apple and occurred in 16 orchards, with two or three generations per year. Nymphs first emerged from overwintered eggs near full bloom, but variation in timing occurred between orchards and years. Population densities of C. verbasci were higher (P<0.05) in unsprayed than in sprayed orchards, but no differences were observed between commercial and “organic” orchards. In June, some adults moved onto herbaceous plant hosts, primarily common mullein, Verbascum thapsus L. Two generations of C. verbasci were found on mullein and the bugs were distributed in an aggregated pattern. Significant associations occurred among height, raceme length, or flower number of mullein plants and the number of C. verbasci on them. From mid-August to October, adult numbers declined on mullein and increased on apple. The number of mullein plants per orchard was not always associated with the density of overwintered C. verbasci in the following year.

show abstract

“…North Carolina has led the way in monitoring weed populations in cover crops (Conn et al, 1982). Other states have initiated cover crop research projects and weed sampling programs (Whalon and Croft, 1984).…”

Section: Samplingmentioning

confidence: 99%

Integrated pest management in tree fruit crops

Brunner

1994

Food Reviews International

View full text Add to dashboard Cite

Selection of Sampling Methods to Determine Weed Abundance in Apple (Malus domestica) Orchards

Cited by 7 publications

References 1 publication

Evaluating field‐scale sampling methods for the estimation of mean plant densities of weeds

Evaluating field‐scale sampling methods for the estimation of mean plant densities of weeds

SEASONAL ABUNDANCE OF THE MULLEIN BUG, CAMPYLOMMA VERBASCI (MEYER) (HETEROPTERA: MIRIDAE), ON APPLE AND MULLEIN IN THE OKANAGAN VALLEY

Integrated pest management in tree fruit crops

Contact Info

Product

Resources

About