Orchard Trials Research Articles

THE EFFECTS OF CHEMICAL FUMIGANTS, NITROGEN, PLASTIC MULCH AND METALAXYL ON THE ESTABLISHMENT OF YOUNG APPLE TREES IN APPLE REPLANT DISEASE SOIL

Postplanting weekly or biweekly applications of metalaxyl at 0.312 mg or 0.600 mg a.i. L−1 soil were as effective as steam sterilization in controlling apple replant disease (ARD) symptoms in greenhouse studies. Growth improvements obtained with metalaxyl suggest that Oomycetes may be involved in ARD in Quebec. In orchard trials plastic mulch, as a cultural treatment, was found to be as effective as methyl bromide, chloropicrin and formalin against ARD; metalaxyl, Vorlex and nitrogen were found to be less effective.Key words: Replant, apple, Malus pumila Mill., Pythium, mulch

Orchard trials on the control of apple collar rot

SummaryTreating apple collar rot (Phytophthora cactorum) lesions with creosote, Pancil T (2-n-octyl-4-isothiazolin-3-one) or a paste of Bordeaux mixture, Ridomil (metalaxyl + copper) or Aliette (fosetyl-aluminium) after removing diseased bark and a 5-cm border of healthy bark (complete surgery) cured 53, 54, 62, 69 and 100% of lesions respectively. Santar (mercuric oxide) applied to a channel cut in the bark around the lesion (ring surgery) cured 81 % of lesions. Aliette paste was a highly effective cure when applied after removing only diseased bark (partial surgery) or after ring surgery. Applying a weaker Aliette preparation to holes drilled down to the wood around the edge of lesions was not an effective cure when holes were 5–8 cm apart and only approached complete effectiveness when the distance between holes was reduced to c. 2 cm. Neither one nor two foliar sprays of Aliette had a statistically significant effect on collar rot lesions. Aliette pr Ridomil applied to lesions after superficial or no ...

Fungicidal control of rust of French prune caused by Tranzschelia discolor

An orchard spray trial indicated that the dithiocarbamates mancozeb and zineb, the latter with or without the addition of white oil as a sticker, gave superior control of prune rust to dithianon, captafol or triforine. Further orchard studies involving artificial inoculation supported this result, with mancozeb and zineb giving 12-13 weeks of complete protection in one instance. In these studies chlorothalonil and bitertanol were also superior to dithianon and captafol, but appeared to be less persistent than the dithiocarbamates. Propiconazole and RH-3866 were relatively ineffective protectants.The efficacies and persistence of fungicides appeared to be less the later they were applied in spring and summer. Rain within a day or two of spraying appeared to reduce fungicide efficacy and persistence, but when it occurred some days or weeks later there was little effect, even a heavy fall (53 mm) not causing an observable reduction in efficacy. The implications of these findings for the development of control strategies is discussed.

Effects of permethrin sprays on the mite fauna of apple orchards

SUMMARYIn two apple orchard trials, single high volume sprays of 25–50 mg permethrin/ litre greatly reduced numbers of the phytosend predatory mite Typhlodromus pyri whether the spray was timed pre‐bloom at growth stages from ‘bud‐burst’ to ‘late green cluster’ or post‐bloom in June. At ‘bud‐burst’T. pyri were partially protected in hibernating sites on the bark, but the lethal effect of the spray was only delayed; no appreciable selectivity could be obtained by this early timing. Bioassays showed that the persistent toxicity of permethrin residues on bark or on leaves declined to a low level within 20 days, and was related to the decline in residue levels determined by G.C. analyses. Residues were detectable for 3 months or longer. Resurgence of spider mites, Panonychus ulmi, occurred within 2 months after all spray timings, and effective predation by T. pyri was only fully re‐establised after several months. In one trial, apple rust mite, Aculus schlechtendali also increased when T. pyri was reduced by spraying. Tydeid mites were killed by permethrin.

Apple rootstock studies. I. Preliminary evaluations of several MM.106 × M.27 hybrids

SummaryVegetatively propagated clones of Malus pumila Mill., selected from the progeny of crosses made between the apple rootstocks MM. 106 and M.27 in 1962 and 1964, were evaluated for potential vigour as rootstocks, ease of propagation, formation of suckers or burr knots and resistance to pests and diseases. Fifteen of these clones were compared with M.9, M.26 and MM. 106 as rootstocks for the apple scion cv Cox’s Orange Pippin in an orchard trial lasting seven years. Most of the clones produced trees of similar size to those formed on MM.106 and some of these, 86.1.25, 86.1.20, 86.1.11 and 10.3.2, cropped very well and exhibited other useful rootstock attributes. One clone, 86.1.24, produced trees smaller than those on M.26 and another, 10.2.5, formed trees smaller than those on M.9. The attributes of all the selections tested are discussed.

Responses of citrus (Citrus sinensis) to nitrogen-phosphorus-potassium (NPK) fertiliser on 2 soils of Rarotonga, Cook Islands 2. Effects of NPK fertiliser rate, soil properties, and leaf nutrient levels on yield and tree size

Abstract The application of increasing rates of nitrogen-phosphorus-potassium (NPK) fertiliser to citrus (Citrus sinensis (L.) Osbeck) resulted in significantly increased overall fruit yields from 4 trial orchards on 2 soil types of Rarotonga, Cook Islands. In 2 of the trial orchards, higher fertiliser rates consistently resulted in significant increases in fruit yields. For these 2 orchards, yields were positively correlated with leaf N levels, negatively correlated with leaf P and K levels, and uncorrelated with leaf sulphur (S) levels. These correlations, which occurred even though higher fertiliser rates resulted in comparatively higher soil levels of P, K, and S, suggest that the increased yields resulted from the increased fertiliser N input. Decreased leaf P and K levels at higher fertiliser rates appeared to be caused by increased translocation of these nutrients from the leaves to the fruit, because of higher fruit yields. On one of the 2 soil types, fruit yields were also positively correlated w...

Interaction between gibberellin A4/7 and root-pruning on the reproductive and vegetative process in Douglas-fir. I. Effects on flowering

In two seed orchard trials, profuse female flowering was induced in young, but ontogenetieally mature grafts of inherently poor-flowering clones (1979) and in 9-year-old seedling-origin trees of both good- and poor-flowering families (1981) of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) by the cultural treatment of root-pruning in conjunction with stem injections of the gibberellin A4 and A7 (GA4/7) mixture. Promotion of male flowering, however, was confined to the more sexually mature grafts. As an individual treatment in the 1981 study, root-pruning was more effective than GA4/7, particularly for the poor-flowering families which did not respond well to GA4/7 alone. The two treatments combined had a highly synergistic effect on both male and female flowering, the synergism being relatively greater for the poor-flowering than for the good-flowering families. Although GA4/7 was not tested alone on grafted propagules, its use with root-pruning enhanced an already significant increase in seed- and pollen-cone buds from root-pruning alone by 540 and 92%, respectively. These and subsequent trials have shown root-pruning +GA4/7 to be a most effective cone-bud enhancement treatment for use in young Douglas-fir breeding and seed production orchards.

The effect of orchard factors on the chemical composition of apples. V. Year-to-year variations in the effects of NPK fertilizers and sward treatment on fruit composition

SummaryNitrogen, P, K, Mg, Ca, Na, titratable acidity and dry weight were measured in 11 successive crops of Cox’s Orange Pippin apple fruit from an N,P,K fertilizer and grass/cultivation orchard management trial. Yearly fluctuations in the concentrations of the constituents were often larger than differences due to experimental treatments. Concentrations of Na were especially variable from year to year and those of Mg followed a biennial pattern. There were also large variations in responses to treatments in different years: in some instances treatment effects were reversed. The varying responses of different constituents to treatments resulted in alterations in the relationships of K to Mg or titratable acid concentrations and Ca concentrations to mean fruit weight in some years. No simple interpretation of these fluctuations was possible in terms of meteorological data.

Efficiency of triforine and binapacryl in tank mixtures with calcium chloride against apple powdery mildew

AbstractThe mildew fungicide triforine is incompatible with calcium chloride used to reduce the incidence of bitter pit in apples. Two commercial non‐ionic surfactants delayed sedimentation in spray mixtures containing both triforine and calcium chloride. The biological efficiency of triforine, alone or with calcium chloride plus surfactant, was tested in an orchard trial which included binapacryl, alone or with calcium chloride, as ‘standard’ treatment. Triforine (weekly or fortnightly) controlled mildew on Cox's Orange Pippin and Golden Delicious better than binapacryl, and the addition of calcium chloride did not affect adversely the control by either fungicide. The added calcium chloride had little effect on the deposition and persistence of the fungicides. The inclusion of calcium chloride in spray programmes slightly improved the yields (both cultivars) and russet grade (Cox only) associated with each fungicide. Calcium chloride sprays, whether mixed or alternated, increased the calcium levels in postharvest fruit for both varieties, and decreased the incidence of bitter pit for Cox after storage for 5½ months. No adverse effect was associated with the inclusion of the surfactants in tank mixtures containing either fungicide.

Promalin improves the shape of Delicious apples in Victoria

Results of two experiments and nine orchard trials over three seasons at eight fruit growing districts have shown that fruit shape of Richared, Lalla, Starking, Hi-Early and Common Delicious apples can be improved by applications of the commercial formulation of N-(phenylmethylkl H-purin-61 - 1 amine plus gibberellins A, + A, (Promalin). Promalin at 25 ppm significantiy increased both fruit length: diameter ratio and prominence of calyx lobes. These fruit were considered to have a more characteristic shape and thus said to be more 'typey'. Response varied between strains, and applications during early stages of flowering were more effective than applications after full bloom. The spraying of Promalin with a hand gun caused heavy overthinning and retention of many small fruit on the tree. Applications with air blast spray equipment at spray volumes of 750-1 100 I/ha gave good results. Some air blast applications induced mild fruit thinning, and in several cases seed number was reduced and stem length increased.

Responses of Scab-resistant Derivatives of Malus Species to Infection with Common Viruses1

Abstract Of 31 preliminary selections from the Geneva scab-resistance apple breeding program inoculated with apple chlorotic leaf spot virus (CLSV), 18 clones exhibited sensitivity during the first 2 growing seasons. Six advanced selections, all derivatives of the virus-sensitive Malus floribunda 821, were inoculated with CLSV or with a combination of other graft-transmissible agents that occur commonly as latent infections in apple. None of the 6 exhibited visible symptoms associated with virus content during 3 growing seasons; growth of 1 selection was slightly depressed. In a 3rd test, 1 of 7 advanced selections derived from M. floribunda exhibited depressed growth in an orchard trial on virus-infected Mailing (M) 9 rootstocks, compared to growth on virus-free M 9.

An aerosol spray gun for the manual pollination of fruit blossom

SummaryThe modification and use of an aerosol spray gun for pollen application in fruit crops is described. Highly significant increases in fruit-set on apple were achieved in an orchard trial. Alder pollen is recommended as a diluent.

Comparison of French and Oriental rootstocks for the Packham's Triumph pear at Bathurst, New South Wales

Of eleven rootstocks tested with Packham's Triumph pear over twenty two years in an orchard trial at Bathurst, New South Wales, P. calleryana stocks were superior to those of P. pashia and P. communis. All five strains of P. caueryana produced more vigorous and better cropping frees than P. pashia which performed better than P. communis seedlings (from varieties Winter Bartlett, Beurre Bosc, Winter Cole), and the East Mulling selection B1. These latter stock were unsatisfactory. Of the five clonal strains of P. calleryana the D6 and PC4 strains produced the most vigorous and highest yielding trees. D6 performed equally well whether as clonal stock or as seedlings.

Recent Developments in the Insecticidal Control of the Apple Maggot1

Chemicals exhibiting a high degree of toxicity to adults of the apple maggot, Rhagoletis pomonella (Walsh), in laboratory tests included Dow M361, Dow ET-14, Dow ET-15, Diazinon®, Pirazinon®, Dipterex®, endrin, isodrin, ethion, Thiodan®, Bayer 25141, phosphamidon, Dibrom®, Phosdrin®, Guthion® and dimethoate. Of these, Dow ET-14, Dow ET-15, Diazinon, Pirazinon, Dipterex, endrin and isodrin brought about the most rapid kill. Other materials tested in the laboratory that showed I-(oodto moderate toxicity to the flies were Chlorthion®, DDVP, Sevin®, Trithion® and Di-Syston®. Phostex® and Ryania were the least effective insecticides used in the laboratory tests. In orchard trials, insecticides were applied as foliage sprays timed according to fly emergence. Isolated orchards, receiving a single schedule of treatments throughout the entire block, were used, as well as multiple-plat experiments that included unsprayed check plats. Migrant flies did not present a problem in pints buffered by a single row of sprayed trees. Spray schedules employing a combination of lead arsenate and Perthane®, Diazinon alone and combined with DDT, DDT plus lead arsenate, Guthion alone, and Guthion plus Sevin, or Guthion plus lead arsenate were effective when used in practicable amounts. Sevin and dimethoate prevented most. larval development within the fruit but permitted puncturing by ovipositing flies and, therefore, are not considered acceptable for commercial use at the rates tested. Strobane® and Bayer 22408, while reducing injury, did not provide sufficient. protection to warrant. further trial. A combination, at reduced levels, of Trithion and DDT, also gave inadequate control, but a schedule including DDT, alone and combined with lead arsenate with one application of Trithion alone was effective. As used in these tests, phosphamidon, ethion, malathion, Diazinon in a two-application schedule, and Diazinon combined with malathion failed to control apple maggot. Sevin combined with lead arsenate failed in one test but, when Guthion was substituted in one application, gave satisfactory control in another. Most failures, under orchard conditions appear to result from inadequate residual lethal action. The chemical names for the insecticides mentioned above for which no approved common names are available are as follows: Bayer 22408—O,O-oiethyl O-naphthalilmido phosphorothioate Bayer 25141—O,O-oiethyl O-p-(methylsulfinyl) phenyl phosphorothioate Chlorthion—O-(3-Chloro-4-nitrophenyl) O,O-dilnethyl phosphorothioate Diazinon—O,O-diethyl O-(2-isopropy 1-6-methyl-4-pyrimidinyl) phosphorothioate Dibrom—1,2-dibromo-2,2-diehloroethyl dimethyl phosphate Dipterex—dimethyl (2,2,2-trichloro-1-hydroxyethyl) phosphonate Di-Syston—O,O-diethyl S-2-(ethylthio) ethyl phosphorodithioate Dow ET-14—O,O-dimethyl O-2,4,5-trichlorophenyl phospholorthioate Dow ET-15—O-methyl 0-2,4,5-trichlorophenyl phosphora midothioate Dow M861—O-methyl 0-2,4,5-trichlorophenyl N-ethyl phosphoramidothioate Guthion—O,O-dimethyl S-(4-oxo-1,2,3-benzotriazin-3-(4H)-yl-methyl) phosphorodithioate Perthane—1,1-dichloro-2, 2-bis(p-ethylphenyl)ethane Phosdrin—1-methoxycarbonyl-1-propen-2-yldinwthyl phosphate (and related compounds) Phostex—a mixture of his (dialkyoxyphosphinothioyl) disulfides Pirazinon—O,O-diethyl-O-3-(2-propyl-6-methyl-4-pyrimidinyl) phosphorothioate Sevin—1-naphthyl N-methylcarbamate Strobane—a mixture of chlorinated terpenes with 66% chlorine Thiodan—6,7,8,9,10,10-hexachloro-1,5,5a6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin-3-oxide Trithion—S-(p-chlorophenylthio)methyl O,O-d iethyl phosphorodithioate

Control of the Apple Aphid and the Rosy Apple Aphid with New Spray Chemicals

Orchard trials with new spray chemicals for thc control of the rosy apple aphid ( Anuraphis roseus Baker) and the apple aphid ( Aphis pomi De Geer) were conducted on Yellow Newtown and Red Delicious apples during 1957 and 1958. Delayed dormant sprays against eggs of the rosy apple aphid demonstrated that ethion-oil, Phostex®,(a mixture of bis (dialkyloxyphosphinothioyl) disulfides)-oil, and Trithion® ( S -( p -chlorophenylthio) methyl O,O -diethyl phosphorodithioate)-oil gave control equal to the standard oil-dinitro sprays, and did not injure thc cover crop. Foilage treatments for the rosy apple aphid in 1957 and 1958 indicated that systemic compounds, demeton, Thimet® ( O,O- diethyl S -(ethylthio) methyl phosphorodithioate), dimethoate Am. Cyanamid 18706® ( O,O - dimethyl S(N-ethyl carbamoylmethyl) phosphorodithioate), and Di-syston® ( O,O -diethyl S -2-(ethylthio)-ethyl phosphorodithioate) would provide good control. Diazinon® ( O,O -diethyl O - (2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothiate) was the only nonsystemic material to provide control of the rosy apple aphid. Guthion® ( O,O -dimethyl S -( 4-oxo-3 H -1,2,S-benzotriazine- 3-methyl) phosphorodithioate), Sevin® (N-methyl-1-naththyl carbamate), Rohm-Haas C-140® (dimethyl carbamate of 2- dimethylaminomethylphenol hydrochloride), ethion, and Thiodan® (6,7,8,9, 10,10-hcxachloro-1, 5, 5a, 6,9,9a-hexahydro-6, 9- methano-2,4,S-benzodioxathiepin-3-oxide) were not effective. Summer treatments for control of apple aphid were applied during the 1957and 1958 seasons. Apple aphid does not become a problem until June, and repeated re infestation makes control difficult. The systemic compounds Thimet, Di-syston, Am. Cyanamid 18706, and dimethoate provided the best control. Nonsystemic compounds, although reducing populations following thc application, did not prevent re infestation and rapid buildup.

Investigations with New Insecticides for Codling Moth Control

Orchard trials with new insecticides for control of codling moth (Carpocapsa pomonella (L.)) on pears were conducted in two orchards in northern California during 1956. Diazinon alone, a combination of Diazinon and DDT, Thimet, Dipterex and a spore preparation of Bacillus thuringiensis Berliner failed to give satisfactory control. Trithion gave variable results, showing promise in one trial, but providing poor control in another. Hercules AC-528 showed some promise, and ryania, Sevin (N-methyl-l-naphthyl carbamate) and Guthion gave codling moth control comparable to the standard dosage of DDT. During 1957, orchard trials were continued on pears, and Sevin and Guthion gave good codling moth control. Guthion also controlled the European red mite (Panonychus ulmi (Koch)), and both Guthion and Sevin reduced a lepidopterous leaf miner infestation to a low level. Ryania, at a low dosage, plus a spreader-sticker, failed to provide adequate reduction of fruit injury by the cooling moth. In a New town Pippin apple orchard, a heavy codling moth infestation was found following grower application of a full DDT program. Field trials during 1957 in this orchard with DDT strongly indicated a resistance to this compound. In the same orchard, Trithion, ryania, Sevin and ethion provided satisfactory control of a heavy infestation. Trithion and ethion also provided control of European red mite, and Sevin prevented a build-up of the apple aphid Aphis pomi DeG. No serious phytotoxic effects were noted on pears or apples following the use of the experimental insecticides.

Stock and Scion Investigations: IX. Twelve Years of Rootstock Effect in an Apple Orchard Trial

Stock and Scion Investigations: IX. Twelve Years of Rootstock Effect in an Apple Orchard Trial

Variation in the yields of fruit trees in relation to the planning of future experiments

does not appear. First page follows. The yields resulting from field trials have, in many cases, indicated the varying responses of plants to soil conditions which appear to be independent of the considerations of the trial. These normal fluctuations in yield constitute a source of experimental error to which all field trials are subject. They are of such importance that they must be taken into account in the planning of such experiments, as well as in the interpretation of the results. In orchard trials such errors may be especially large. The great variation observed is due, in part, to the relatively large area of land involved in a single experiment, with the attendant possibilities of important changes in soil and topography. It is also due in some degree to the individuality of the trees. These two classes of factors ordinarily increase the observed variations greatly above those found in experiments with agronomic crops, for in the latter the use of a large number of plants in a single plot results in practical elimination of the effects of individual plant variation. In addition, the relatively small size of the plots permits them to be located on a small area of land.