Weeds In Orchards Research Articles

Identificação de biótipos de azevém (Lolium multiflorum) resistentes ao herbicida glyphosate em pomares de maçã

O glyphosate é um herbicida de amplo espectro utilizado há mais de 15 anos em pomares de maçã na região de Vacaria-RS, para manejo da vegetação nas linhas da cultura. São realizadas, em geral, três a quatro aplicações por ciclo e a dose normalmente utilizada é de 720 a 1.080 g e.a. ha-1 de glyphosate (2 a 3 L ha-1 do produto comercial). O azevém (Lolium multiflorum) é uma planta daninha comum em pomares e, tradicionalmente, sensível ao glyphosate. Entretanto, nos últimos anos a ocorrência de plantas de azevém que, após receberem o tratamento com glyphosate, não manifestam sintomas significativos de toxicidade sugere que elas adquiriram resistência ao produto. Assim, com o objetivo de avaliar a resposta de uma população de plantas de azevém ao glyphosate, foram realizados três experimentos: um em campo e dois em casa de vegetação. No experimento em campo os tratamentos avaliados constaram de doses crescentes de glyphosate (0, 360, 720, 1.440, 2.880, 5.760 e 11.520 g e.a. ha-1), e os herbicidas paraquat, glufosinate, haloxyfop e diclofop foram empregados como produtos-padrão, aplicados em dois estádios vegetativos do azevém. No experimento em casa de vegetação, os tratamentos constaram de doses crescentes de glyphosate (0, 360, 720, 1.440, 2.880 e 5.760 g e.a. ha-1) mais os herbicidas testemunhas, aplicados sobre plantas do biótipo considerado resistente e de um sensível. No segundo experimento realizado em casa de vegetação foram avaliados tratamentos contendo glyphosate (720, 1.440, 2.880, 720 + 720 e 720 + 1.440 g e.a. ha-1), em aplicações únicas e seqüenciais, mais os herbicidas paraquat, glufosinate, haloxyfop, clethodim, sethoxydim, diclofop, fenoxaprop, fluazifop, paraquat + diuron, atrazine + simazine, trifluralin e metolachlor. A toxicidade dos tratamentos herbicidas foi avaliada aos 15, 30 e 45 DAT (dias após tratamento). Os resultados obtidos nos experimentos em campo e em casa de vegetação, de forma geral, evidenciam que o biótipo sensível é facilmente controlado com o herbicida glyphosate e pelos demais herbicidas pós-emergentes avaliados, independentemente do estádio vegetativo. Demonstram, ainda, que o biótipo resistente apresenta-se, igualmente ao biótipo sensível, altamente suscetível aos herbicidas com mecanismo de ação distinto daquele do glyphosate. No entanto, o biótipo resistente apresenta baixa resposta ao herbicida glyphosate, mesmo se este for empregado em altas doses, evidenciando ter adquirido resistência a esse produto.

Effect of two different thermal units and three types of mulch on weeds in apple orchards

The effect of two different thermal units (flame and hot steam) and three types of mulch on the percentage of weeds killed was studied in a series of experiments over 2 years. The factors studied were driving speed (2, 3, 4 km/h), flame treatment (first, second, third), growth stage (<6, 6–8, >8 true leaves), hot steam treatment (single, double), mulch type (none, coarse bark, sawdust, hay), and chemical application. The results suggest that a driving speed of 2 km/h kills the highest percentage of weeds, and for weed species with unprotected growth points and thin leaves, the first flame application can completely kill weeds with <6 leaves. However, a second or third flame application is required for those with 6 or more leaves. The hot steam method is effective when it is applied twice, with the second application 1 week after the first. However, there is room for improving its technology to make it cost effective for large-scale applications. Mulches after chemical herbicide application are effective for controlling weeds. However, mulching cannot be recommended with flaming because of fire hazard. The effectiveness of herbicide depends on the weed species and on whether the same herbicide was used in the preceding years. Compared to using herbicide with mulching, herbicide alone was less effective in controlling weeds and more costly in terms of cost per hectare and the environment. Key words: thermal weed control, flame, hot steam, mulching, herbicides, apple orchard, logit models.

New generation of protox-inhibiting herbicides

Benzfendizone belongs to the 2-[(4-heterocyclic-phenoxymethyl)-phenoxy]alkanoate class of herbicides which are potent inhibitors of the plant enzyme protoporphyrinogen oxidase (Protox). Benzfendizone, when applied postemergence, provides control of a number of key grass and broadleaf weeds in orchards and no-till crop situations. Benzfendizone can also be used as a potato desiccant and cotton defoliant. Crops such as soyabean and corn showed no injury when planted 2–3 days following postemergence application of benzfendizone.

Weed management practices in apple orchards and vineyards in the South Island of New Zealand

A survey of weeds and weed management practices was conducted during 1997/98 in apple orchards and vineyards of Canterbury and Nelson/Marlborough regions of New Zealand. According to growers, mallow (Malva spp.) ranked as the most widespread weed in apple orchards of both regions. In vineyards, mallow was the most common weed in Nelson/Marlborough and the second most common weed in Canterbury. Other dominant weeds in Nelson/Marlborough included grasses, black nightshade (Solarium nigrum), fathen (Chenopodium album), and redroot (Amaranthus retroflexus). In Canterbury, grasses, clovers, fathen, and thistles were common. In almost all orchards knockdown herbicides were used but the use of residual herbicides varied. The total number of herbicide applications/year has increased in both regions over the past 10 years, but the proportional use of residual herbicides has declined. Some other weed management practices are used in orchards but a sound integration of these is commonly lacking.

Effect of Timing of Winter Weed Control on the Growth of Young Peach Trees under Sod Culture.

A census of the weed population by species and their coverage and heights was made periodically over the summer in fruit trees and grapevines to characterize the vegetation of winter annual weeds in sunny orchards (Exp. 1). The timing of herbicide applications on the reduction of competition between winter annuals and the growth of 1-yr-old 'Hikawahakuho' peach (Prunus persica Batsch. var. vulgaris Maxim.) trees was studied (Exp. 2). The competition between those weeds and 4- and 6-yr-old 'Hikawahakuho' peach trees was also examined incorporating various vegetation management practices (Exp. 3). When weed management allowed winter annual weeds to grow freely in young sunny orchards, Vicia angustifolia L. became dominant from March to June, followed by Stellaria media (L.) Villars, and Lamium amplexicaule L. Those winter weeds reduced the overall growth of 1-yr-old peach trees when they were not controlled by May. Growth inhibition of newly developing shoots and fine roots by winter weeds was not as strong as that by summer weeds. Shoot length was reduced significantly in 4-yr-old peach trees but not in 6-yr-old ones. The results indicate that winter weeds need to be controlled by early May to minimize inhibition of peach tree growth.

Soil nitrate levels as influenced by apple orchard floor management systems

Mulches are an alternative to herbicidal control of weeds in orchards. Mulches may affect soil nutrient levels and consequently alter tree growth, fruit yield, and quality. The objective of this study was to determine the effects of cultivation, straw mulch, geotextile mulch, grass cover, a cover crop mixture of lupin and wild carrot, and manure compost mulch on extractable soil nutrients in two newly established dwarf apple orchards in Quebec. In 1992, manure compost and straw mulches resulted in higher soil NO3−-N and K relative to those levels under ground cover. Levels of soil NO3−-N were related to soil water content under any particular mulch. Straw mulch resulted in high July NO3−-N levels and low September levels of soil NO3−-N. Geotextile and cultivation treatments resulted in higher September NO3−-N levels relative to July. Soil under manure compost tended to have higher P levels than soil under other treatments. There was little or no effect of mulch treatments on extractable levels of soil NH4+-N, Ca, or Mg. Key words: Orchard, apple, mulches, geotextiles, straw, nutrients, manure compost, grass sod

Seasonal Phenology and Biology of Calocoris norvegicus (Hemiptera: Miridae) in Pistachios and Associated Host Plants

The biology and seasonal phenology of Caloeoris norvegieus (Gmelin) were studied in pistachios, Pistaeia vera L., and associated host plants in the laboratory and four orchards in the Sacramento Valley. Nymphs were found in weeds in the orchards from late March; adults were found in early April and disappeared by late May. In beating-tray samples, adults were observed on pistachio clusters from 12 April until 25 May. Increases in numbers of adults in the beating-tray samples corresponded to high levels of epicarp lesion, ranging from 11 to 34%. Dispersal to pistachios coincided with the development of adults and was correlated with the drying of orchard weeds or cutting of alfalfa. C. norvegicus nymphs and adults were recorded on various host plants, which included several species of legumes, mustards, and orchard grasses. In late March, first instars hatched from diapausing eggs laid in the dried stems of wild radish, Raphanus sativus L., and wheat, Triticum aestivum L. Neither eggs nor first instars were found on pistachio limbs. In the laboratory, survival to adulthood was 92-98% on winter vetch, View villosa Roth, curly dock, Rumex erispus L., and wild radish, and 25% in wild oats, Avena fatua L. Oviposition was observed within all herbaceous hosts except wild oats.

Demography and Growth Forms of the Clonal Perennial Rubia Peregrina in Mediterranean Vineyard and Unmanaged Habitats

SUMMARY (1) During a two-year study, the dynamics of genets, ramets and aerial metamers (leaf whorl+ internode) and the growth forms of three populations of Rubia peregrina, a mediterranean rhizomatous perennial, were compared in a vineyard, a degraded open sward and under a Quercus ilex canopy. (2) The weedy vineyard population increased in size (the relative rate of change of ramets over the period of study was 1 8) whereas the two non-weedy populations were in a more-or-less steady-state (relative rates of change were -01 1 and 0-23 for the sward and oakwood populations, respectively). No establishment of new genets was observed. (3) In the three habitats, the production of ramets and metamers was maximal during spring and autumn; during summer, it stopped in unmanaged habitats, while a small rate of production was still observed in the vineyard. In all habitats, mortality was high during active growth periods and, especially in the sward, during summer drought. Death of ramets was density independent in the vineyard and sward. (4) In the vineyard, R. peregrina showed a phalanx growth form, with a high density of closely packed ramets; under the oak canopy it showed a guerrilla growth form with lower density of more widely spaced ramets; in the degraded open sward, an intermediate growth form was observed. The results show that the compact architecture of the phalanx type is enhanced by the high degree of branching of modules bearing short and numerous metamers, and that opposite traits predominate in the guerrilla type. In addition, half-lives of metamers were inversely related to their size. Thus, it is suggested that the morphology of ramets and demography of aerial metamers should be integrated in the definitions of growth forms. (5) For the whole data set, a positive linear relationship (P < 0 001) was found between half-lives of metamers and internode length and a negative linear relationship (P < 0 003) between internode length and degree of branching of ramets. (6) The differences in growth forms between the unmanaged and agricultural habitats may be due to competition and resource availability. It is suggested that species tolerant of herbicides and displaying a phalanx growth form are potentially injurious weeds in vineyards and orchards where minimum tillage is practised.

Determination of atrazine residues in food by enzyme immunoassay.

Atrazine (6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-trlazlne-2,4diamlne), a trlazine herbicide, Is used to control annual grasses and broad-leaf weeds in corn, pineapple, sugarcane and macadamla orchards. Thls herbicide Is used extenslvely worldwlde. In the Unlted States atrazine is the second most applled pestlclde; approximately 79 million pounds is used annually (Anonymous). Although It fs allowed on only four agricultural commodlties for human consumptlon, many more crops are exposed to atrazine from soll carry over in rotatlonal programs. Because of Its extensive use and llmlted toxicological data (Wilson et al. 1987), there fs a need for monltorlng food for atrazlne resldues.

Oviposition by the banded fruit weevil, Phlyctinus callosus (Schoenherr) (Coleoptera: Curculionidae), in deciduous fruit orchards in South Africa

AbstractOviposition sites of Phlyctinus callosus (Schoenherr) in an apple and a nectarine orchard in the South Western Cape, South Africa, were investigated. No eggs were found on the fruit trees, only in different fractions of the orchard floor, viz. in orchard weeds, leaf litter and soil. Significantly more oviposition took place in plant material on the orchard floor than in the top 20 mm of the soil. Microscopic dissection of samples of such plant material revealed that females prefer to oviposit in confined or hollow spaces in moist, live or decaying plant tissue on the soil surface or in weeds comprising the cover-crop. P. callosus females favoured certain weeds above others for oviposition. The dispersion pattern of eggs in the cover-crop was contagious. The implications of the observed ovipostion behaviour in terms of control strategy, and for exploitation in a monitoring system for this species, are discussed.

Biological-Control of Tetranychus-Urticae (Koch) (Acari, Tetranychidae) in Southern New-South-Wales Peach Orchards - the Role of Amblyseius-Victoriensis (Acarina, Phytoseiidae)

Populations of mite predators and Tetranychus urticae (Tetranychidae) occurring in peach orchards on two farms at Leeton, New South Wales, were monitored during 1987/88. In both orchards the key pest Cydia molesta (Busck) (Tortricidae) was controlled by a pheromonal mating disruption strategy which avoided the use of broad-spectrum insecticides. During both years substantial populations of a native predatory mite, Amblyseius victoriensis were associated with an absence or very low populations of T. urticae from mid-summer until leaf fall. During spring 1987 some control of T. urticae was provided by a suite of predatory insects. Late spring applications of fungicide delayed development of A. victoriensis populations and a mid-summer miticide spray delayed establishment of the predator. Typhlodromus occidentalis occurred only when A. victoriensis populations were low or eradicated by sprays. During autumn, 1987 A. victoriensis occurred on orchard weeds but populations declined to a low level during winter. Substantial overwintering populations of reproductive T. urticae occurred on weeds and invaded the trees at bud burst. The generalist feeding behaviour of A. victoriensis is considered to be the key to the success of this predator. Dependence on biological control for T. urticae management is considered to be a practical option for southern New South Wales peach orchardists.

Apple, Herbicide Effects on Mites, 1985

Abstract A 2.5ha (1A) apple block at Steeles Tavern was put on a differential herbicide regime for the second year. Half of the block was treated with simazine, a herbicide which is nontoxic to AF. The remainder of the block was treated with simazine plus paraquat, a herbicide known to be toxic to AF. Applications were made on 13 May, using a power take off orchard weed sprayer. Label rates were used in (100 gal/A). Both treatments included X-77 surfactant at the rate of 62 ml/100 liters (8 oz/100 gal). Mites were sampled on 15 Jul and 23 Jul, using one 20-leaf sample from each of 6 trees per treatment.

A Comparison of Capture-Recapture with Capture-Removal for Quail Populations

The effects of paraquat (1,1'-dimethyl-4,4'-bipyridinium dichloride) on reproduction and growth of northern bobwhite (Colinus virginianus) were studied. In the parent generation (P) paraquat was administered at 0, 20, 60, and 180 ppm for 6 weeks. Reproductive variables examined included egg production, fertility, hatchability, chick abnormalities, and chick survival and weights to 7 days of age. Untreated breeders in the second generation (F1) phase were the offspring of the various groups in the first generation phase. Reproductive variables examined included egg production, number of days to first and last egg of a 20-egg clutch, fertility, and hatchability. P hens fed 180 ppm laid fewer eggs (all differences are at P < 0.05) during treatment compared to their pre-treatment period and to controls, and had lower ovary and oviduct weights. There were no differences in P fertility nor in chick abnormalities or survival as compared to controls. Chicks from P parents fed 20 ppm paraquat were heavier than all other treatments. P male and female post-treatment weight did not differ from pre-treatment weight. F, hens from paraquat-treated parents started laying 1 week later than controls and produced eggs at a lower rate resulting in clutch completion 10 days later than controls. There were no differences in F, fertility, hatch, or relative testes, ovary, and oviduct weights. Adult F, hens from parents fed 60 and 180 ppm paraquat weighed less. J. WILDL. MANAGE. 49(4):1066-1073 Paraquat is used extensively throughout the world for the control of weeds in orchards and crop fields and as a crop desiccant. Increased use of paraquat has resulted from an increase in no-tillage agriculture. Paraquat is available in the United States primarily as paraquat dichloride, a 29.1% liquid concentrate containing 0.9 kg paraquat cation/3.8 liter. The recommended field application rate usually ranges from 0.28 to 1.12 kg paraquat cation/ha (Ortho Tech. Inf., Chevron Chem. Co., Richmond, Calif., 1974). Residues of about 30 ppm in alfalfa and 60 ppm in adventitious graminaceae have been found after paraquat treatment at a r commended field level (De Lavaur et al. 1973). Paraquat residues have been reported to be as high as 1,000 ppm in herbage on grazing plots treated with the highest recommended application level (Calderbank et al. 1968). Some wildlife species may be affected by recommended field application rates of paraquat (Ernest 1971, De Lavaur et al. 1973, Dial and Bauer 1984). De Lavaur et al. (1973) found that 50% of hares (Lepus europaeus) exposed to alThis content downloaded from 157.55.39.83 on Sun, 09 Oct 2016 05:00:36 UTC All use subject to http://about.jstor.org/terms

Effect of Orchard Weed Management on Catfacing Damage to Peaches in North Carolina

Regression analysis on data from a 1981 survey of commercial peach orchards in North Carolina demonstrated a significant correlation between catfacing damage and chemical insect control, weed management, density of winter annuals, orchard size, and geographic location. Cultivar, surrounding edge vegetation, and edge direction showed no correlation with damage. In 1983, two commercial orchards were used to evaluate the impact of weed management on the incidence of catfacing in peaches. A χ2 analysis of data showed amount of fruit damaged by catfacing in herbicide-treated blocks to be significantly less than that of fruit sampled from control blocks.

Gradient analysis and numerical classification of apple orchard weed vegetation

Importance values based on cover and frequency were determined for 36 weed species in understory samples from 47 apple orchards located in Henderson County, North Carolina. Orchard sub-groups identified by cluster analysis of the weed composition data included two major groupings dominated by grasses and woody perennials, respectively. Ordination by detrended correspondence analysis (DECORANA) was used to extract axes of compositional variation in orchard weed vegetation. Orchard sub-groups identified by cluster analysis could be recognized in the DECORANA ordinations. All grasses, most perennial forbs and all summer-annual forbs decreased in importance along a first ordination axis based upon data from 43 orchards. Two perennial forbs and all woody perennials increased in importance along the same axis, while species-richness of weeds declined. Results of multiple regression indicated that the annual frequency of paraquat application from 1976 to 1979 was the single factor accounting for the greatest compositional variation in the first two axes of the 43-orchard ordination. Tree canopy width and in-row spacing, total extractable soil cations, and percentage soil organic matter also accounted for significant amounts of variation in weed composition. Similar results were obtained from models developed for an ordination of the 35 grass-dominated orchards, suggesting the importance of management, structural and soil factors in determining weed composition in apple orchards.

Orchard Weeds as Hosts of Tomato Ringspot and Tobacco Ringspot Viruses

Orchard Weeds as Hosts of Tomato Ringspot and Tobacco Ringspot Viruses

Orchard Weeds as Hosts of Tomato Ringspot and Tobacco Ringspot Viruses

Orchard Weeds as Hosts of Tomato Ringspot and Tobacco Ringspot Viruses

Green Peach Aphid 1 : Orchard Weeds are Host to Fundatrix 2

Malva neglecta Wallr. and Descurainia sophia (L.) Webb ex Prantl, common weed species growing in the orchard at the same time that eggs of the green peach aphid (GPA), Myzus persicae (Sulzer), are hatching on peach trees and on prunings on the floor of the orchard, supported development and reproduction of hatching fundatrices (stem mothers) in Mar. and Apr. Also, sticky traps hung from peach trees caught large numbers of aphids falling to the ground. Thus, fundatrices of the GPA that fall onto weeds or develop there are the early progenitors of the population buildup on weeds, not the fundatrigeniae (progeny of stem mother) as believed earlier.

Evaluation of Orchard Weed Hosts of Green Peach Aphid 1 and the Production of Winged Migrants

In laboratory tests, only 8–13% survived of 1st-instar nymphs of the green peach aphid (GPA), Myzus persicae (Sulzer), placed on young lambsquarters, Chenopodium album L., and redroot pigweed, Amaranthus retroflexus L., with 2–4 leaves initially and held to adult stage. GPA had 80% survival and shorter developmental time on radish, Raphanus sativus L., shepherdspurse, Capsella bursa-pastoris (L.) Medik, field bindweed, Convolvulus arvenis L., hoary cress, Cardaria draba (L.) Desv., yellowflower pepperweed, Lepidium perfoliatum L., and hairy nightshade, Solanum sarrachoides Sendt. When life table statistics were determined for the 7 weed plants and radish, hoary cress had the highest intrinsic rate of increase, r = 0.401; and that for radish was r = 0.357. In field cage experiments, with plants with 6 true leaves initially, the GPA multiplied faster on shepherdspurse, radish, and hairy nightshade than other weeds. In the orchard, the GPA population in late May on 6 common weed species ranged from 608/pigweed plant to 4659/yellowflower pepperweed plant. Winged migrants contributed from 3.8–26% of these populations and the estimated production of winged GPA was 70 million migrants/ha. Since about half of these orchard weed species are known hosts of beet western yellow virus (BWYV), many of the winged GPA from the orchard weeds are potential vectors of BWYV.

Orchard Soil Management and Weed Control, East Malling Research Station Member's Day, June 1978

Orchard Soil Management and Weed Control, East Malling Research Station Member's Day, June 1978