Petal Fall Spray Research Articles

Refinement of Nonantibiotic Spray Programs for Fire Blight Control in Organic Pome Fruit.

Fire blight-susceptible, certified organic pome fruit is produced on 9,000 ha in the Pacific Northwest region of the United States with acreage continuing to expand despite a 2014 prohibition on antibiotics as allowable materials for infection suppression. Nonantibiotic practices for fire blight pathogen suppression mirror conventional management, but the full-bloom-to-petal-fall period when antibiotics are typically sprayed for fire blight control continues to receive research scrutiny owing to drawbacks and weaknesses of alternative materials. As solitary treatments, effective nonantibiotic materials (e.g., a yeast biocontrol, soluble coppers, and potassium aluminum sulfate) raise the risk of a crop-value-reducing, phytotoxic response termed "fruit russeting." Conversely, materials with less russeting risk (e.g., Bacillus-based biorationals) are less effective for fire blight control. Spray programs using a sequence of materials applied from midbloom to petal fall have the potential to provide high levels of protection with reduced russeting risk. In orchard trials, the effects of nonantibiotic spray programs on the epiphytic population size of Erwinia amylovora in flowers, yeast biocontrol population size, floral pH, infection suppression, and fruit russeting revealed strategies for sequencing sprays of nonantibiotic materials. The yeast biocontrol, Blossom Protect (Aureobasidium pullulans), sprayed at 70% bloom, was an important contributor to fire blight pathogen suppression as was the soluble copper material, Previsto, when applied at full bloom. Choice of material for the petal-fall spray timing was important to fruit russeting risk but apparently less important to overall infection incidence. Consequently, treatment programs of Blossom Protect at 70% bloom, a soluble copper at full bloom, and a Bacillus-based biorational at petal fall, best balance the quality of infection suppression with the risk of fruit russeting.

Toward the Integration of an Attract-and-Kill Approach with Entomopathogenic Nematodes to Control Multiple Life Stages of Plum Curculio (Coleoptera: Curculionidae).

Efforts to reduce insecticide inputs against plum curculio, Conotrachelus nenuphar, a key pest of apples in eastern North America, include perimeter-row insecticide sprays applied after the whole-orchard petal fall spray to manage dispersing adults and, more recently, insecticide sprays confined to odor-baited trap trees. Entomopathogenic nematodes (EPNs) are virulent to ground-dwelling stages of C. nenuphar, and may be applied to the ground underneath trap-tree canopies. Here, we (1) compared the efficacy of the odor-baited trap tree approach with grower-prescribed (=grower standard) sprays to manage C. nenuphar populations over a six-year period in seven commercial apple orchards in New England; and (2) assessed the performance of the EPN Steinernema riobrave at suppressing ground-dwelling stages of C. nenuphar. In addition, the performance of S. riobrave was compared against that of S. carpocapsae and S. feltiae in one year. Across the six years, percent fruit injury on trap tree plots averaged 11.3% on odor-baited trap trees and 1.4% on unbaited trees in grower standard plots, highlighting the ability of trap trees to aggregate C. nenuphar activity and subsequent injury. Mean percentage injury on fruit sampled from interior trees, the strongest measure of treatment performance, in trap tree plots did not differ significantly from that recorded on interior trees in grower standard spray plots (0.95 vs. 0.68%, respectively). Steinernema riobrave consistently reduced C. nenuphar populations as indicated by the significantly lower number of adult C. nenuphar that emerged from the soil, when compared to water control. Steinernema carpocapsae and S. riobrave performed similarly well, and both EPN species outperformed S. feltiae. Our combined findings indicate that an IPM approach that targets multiple life stages of C. nenuphar has the potential to manage this pest more sustainably in a reduced-spray environment.

Horticultural mineral oil applications for apple powdery mildew and codling moth, Cydia pomonella (L.)

Horticultural mineral oil (Orchex 796) was tested in two treatment regimes, either a three-spray early season program targeting apple powdery mildew, Podosphaera leucotricha (All. & Evherh.) Salm. (Oil/Disease treatment) or a six-spray program targeting both generations of codling moth, Cydia pomonella (L.) (Oil/CM treatment), on apple, Malus domestica Borkhausen. These treatments were compared with a check, which received no post-bloom applications of oil. Apple powdery mildew shoot infestation was suppressed only in 1 year of the study (1999) by the Oil/Disease treatment, but no differences in fruit damage were found. The six-spray program of horticultural mineral oil produced the highest percentage of clean fruit, and the lowest level of codling moth-damaged fruit, but only one out of the 3 years of the study. Even in the best treatment in this year, codling moth damage was unacceptably high. Campylomma verbasci (Meyer-Dür) fruit damage was reduced by the oil sprays timed for mildew, probably because of the petal fall spray included in this treatment. Rosy apple aphid, Dysaphis plantaginea (Passerini), densities were suppressed (1 year only) by both oil treatments, while apple aphid, Aphis pomi De Geer, populations were not influenced by oil treatments at any time during the study. White apple leafhopper nymphs, Typhlocyba pomaria McAtee, and tetranychid mite populations were consistently suppressed by both oil treatment regimes, with generally higher levels of suppression occurring with the higher number of applications, despite the lack of specific timing. The same was true of apple rust mite, Aculus schlechtendali (Nalepa), and the western predatory mite, Galandromus occidentalis (Nesbitt).

Chemicals, Timing, and Environmental Factors Involved in Thinner Efficacy on Apple

HORTSCIENCE, VOL. 37(3), JUNE 2002 Fallahi, E., M. Kilby, and J.W. Moon. 1990. Effects of various chemicals on dormancy, maturity and thinning of peaches. Deciduous Fruit and Nut. University of Arizona, College of Agr. Rpt., Ser. P-83, p. 121–128. Fallahi, E., R.R. Lee, and G.A. Lee. 1998. Commercial-scale use of hydrogen cyanamide for blossom thinning of apple and peach. HortTechnology 8:556–560. Fallahi, E., B.R. Simons, J.K. Fellman, W.M. Colt. 1992. Use of hydrogen cyanamide for apple and plum thinning. Plant Growth Regulat. 11:435–439. Fallahi, E., M.W. Williams, and W.M. Colt. 1997. Blossom thinning of ‘Law Rome Beauty’ apple with hydrogen cyanamide and monocarbamide dihydrogensulfate. J. Tree Fruit Prod. 2:33–44. Ferree, D.C. 1996. Performance of benzyladenine as a chemical thinner on eight apple cultivars. J. Tree Fruit Prod. 1:33–50. Greene, D.W. 1984. Microdroplet application of GA4+7 + BA: Sites of absorption and effects on fruit set, size, and shape of ‘Delicious’ apples. J. Amer. Soc. Hort. Sci. 109: 28–30. Greene, D.W., K.I. Hauschild, and J. Krupa. 2001. Effect of blossom thinners on fruit set and fruit size of peaches. HortTechnology 11:179–183. Greene, D.W. and W.J. Lord. 1985. Effects of chemical thinners on ‘Delicious’ apple trees previously sprayed with GA4+7 +BA. HortScience 20:84–86. Hildebrand, E.M. 1944. The mode of action of the pollenicide, Elgetol. Proc. Amer. Soc. Hort. Sci. 45:53–58. Johnson, S. 1998 Consistent tonnage needed for profitability. Good Fruit Grower 49(7):9–10. Looney, N. 1998. Chemical thinning of ‘Fuji’ apple. Compact Fruit Tree. Proc. Annu. Conf. Intl. Dwarf Tree Assn. 30:55–57. Sanderson, P. 1998. Consistent tonnage needed for profitability. Good Fruit Grower 49(7):9-10. Southwick, S.M., K.G. Weis, J.T. Yeager, and M.E. Rupert. 1998. Blossom thinning of ‘Loadel’ cling peach with a surfactant: Effects of concentration, carrier volume, and differential applications within the canopy. HortTechnology 8:55–58. Taylor, J. 1998. Consistent tonnage needed for profitability. Good Fruit Grower 49(7):9-10. Williams, K.M. 1998. Blossom thin for consistent crops. Good Fruit Grower 49(7):8. Williams, M.W. 1993. Comparison of NAA and carbaryl petal–fall sprays of apples. HortTechnology 3:428–429. Williams, M.W. 1994. Factors influencing chemical thinning and update on new chemical thinning agents. Compact Fruit Tree 27:115–122. Williams, M.W. and Edgerton. 1981. Fruit thinning of apples and pears with chemicals. U.S. Dept. Agr., Agr. Bul. 289.

Blossom Thinning in Pome and Stone Fruit

Early thinning of apples is important because of its impact on fruit size and next season's flower bud initiation. In the past, apple cultivars were often sprayed with the blossom thinner sodium dinitro-ortho-cresol(Elgetol) during full bloom, followed by a post-bloom application of a fruit thinner such as carbaryl with or without naphthalene acetic acid (NAA). Elgetol was removed from the market in 1989 because of the high cost of re-registration. Full-bloom sprays of sulfcarbamide (Wilthin), pelargonic acid (Thinex), and endothalic acid (Endothal), ammonium thiosulfate (ATS) or petal fall spray of carbaryl (Sevin XLR Plus) were developed as replacements for Elgetol. Hydrogen cyanamide (HC) and other chemicals have been used to eliminate or to reduce chilling requirements of peaches grown under the warm desert conditions. HC applied at “pink bloom” stage was observed to reduce the number of open blooms in `Florda Prince' peach; therefore, it was first used for blossom thinning in this cultivar in Arizona. Later, HC was also found to be an effective blossom thinner for plums in Idaho. HC has recently been found to effectively thin apple and peach blossoms. Armothin has also been an effective blossom thinner for peach in California.

Comparison of NAA and Carbaryl Petal-fall Sprays on Fruit Set of Apples

Biennial bearing of apple trees can be overcome either by the use of a blossom chemical thinner or by early application of a postbloom thinner. Carbaryl (Sevin) is a post-bloom fruit-thinning chemical with an effective thinning period of 4 to 5 weeks after bloom. Sevin was compared in 1992 and 1993 with NAA as an early petal-fall spray. Sevin treatments reduced fruit set to one fruit per cluster with no adverse side effects on the foliage. NAA inconsistently reduced fruit set and the remaining fruit were in clusters, The NAA-treated foliage was adversely affected; having small curled leaves. NAA at 10 ppm under-thinned in 1992 and seriously over-thinned in 1993, whereas Sevin treatments were consistent for fruit thinning in both years. Sevin applied at petal-fall or at petal-fall + 7 days effectively reduced fruit set and reduced fruit competition.

Sulfcarbamide, A Blossom-thinning Agent for Apples

In fruit-growing areas where pollination and fruit set conditions are optimum, biennial bearing is a regular occurrence unless steps are taken to reduce fruit set in the heavy bloom year. In the past, a two- or three-spray thinning program was used in the state of Washington on difficult cultivars, consisting of Elgetol at bloom time, followed by a petal fall spray of Amide-thin, followed by a later postbloom spray of NAA or Sevin. In 1989, Elgetol was removed from the market by the manufacturer because of the high cost of re-registration. In 1990, a search for an Elgetol replacement was initiated. Elgetol was a contact spray that damaged flower parts and prevented fertilization of the ovule. Thus, it was logical to look for other products that had a similar mode of action. Sulfcarbamide (monocarbamide dihydrogen sulfate) (D-88) (Wilthin), a foliage desiccant used on potatoes, onions, and alfalfa, and tested as a dilute full-volume spray on apple blossoms, was found to be an effective blossom thinner. Chemical rates of 0.25% to 0.5% (v/v) applied at 80% of bloom open reduced fruit set by 25% to 50% compared to controls.

COMPARISON OF NAA AND SEVIN PETAL FALL SPRAYS ON FRUIT SET OF APPLES

In Washington and other western states Elgetol, a blossom thinning agent was previously used before the postbloom NAA and Sevin applications and there was no need for an earlier timing of NAA and Sevin treatments. In 1989, Elgetol was removed from the market by the manufacturer because of minor crop use and the high cost of re-registration. Without a blossom thinner it is impossible to guarantee a return bloom on severe biennial bearing cultivars such as Golden Delicious and Fuji. Even though adequate fruit thinning occurs with the postbloom thinning sprays, flower Initiation may not occur for the next years crop because the application is made too late.NAA and Sevin are used as postbloom sprays for reducing fruit set of apples. The usual time of application is when the largest fruit are from 10 to 15 mm in diameter. Sprays applied at the 10-15 mm fruit diameter stage take advantage of warm weather after spraying which increases stress and maximizes reduction of fruit set with a minimum effect on the seed number, however, when temperature is cold seed abortion occurs without adequate reduction of fruit set.This report compares the efficacy of the postbloom thinners NAA and Sevin as early petal fall sprays for reducing fruit number and increasing return bloom the following year. Sevin is most effective as an apple fruit abscission agent when applied at petal fall. In trials for 2 years there was no reduction in fruit seed number, no reduction in fruit size and no effect on fruit shape. In comparison NAA applied at petal fall tended to reduce seed number, reduce fruit size, flatten or distort fruit shape and cause leaf curling.

Border-Row Sprays for Control of the Plum Curculio in Apple Orchards: Behavioral Study

In spring 1987, 215 65Zn-labeled adult plum curculios, Conotrachelus nenuphar (Herbst), were released, just after they emerged from overwintering, at a single site located at the southern edge of a woodlot bordering an unsprayed apple orchard in southern Quebec. At petal fall, between the second and third day of release, a border-row spray of insecticide was applied to the two perimeter rows of apple trees in front of the release site. Dispersal of the population was compared with another group of 254 curculios released simultaneously in the center of the 1.7-ha orchard. In 1988 and 1989, the borderrow spray was applied to the entire orchard perimeter. Plum curculio damage at harvest was assessed and compared with that found in a nearby unsprayed apple orchard. Labeling had no significant effect on field mortality and behavior. Insects released at the edge of the woodlot moved toward the orchard. Mortality was three times higher for insects dispersing through the sprayed rows than for those dispersing in the center of the orchard. Among insects that were recaptured in the orchard and at its edge, 83% were found either dead under the sprayed trees (59%) or alive along the outside edge of the sprayed rows (24%). The remaining curculios (17%) were found alive within the orchard. Plum curculio damage at harvest decreased from 1987 (52%) to 1989 (2.4%), whereas in a nearby unsprayed apple orchard, it averaged 70% (minimum 43%, maximum 88%). A single petal fall border spray was moderately effective in protecting fruit, but the combination of a pink spray and a petal fall border spray provided economically acceptable control. Reinfestation after the petal fall spray appeared to be the main cause of plum curculio damage at harvest. Toads, Bufo americanus americanus Holbrook, were found with high levels of 65Zn. Ways to improve the efficiency of plum curculio control by border-row spraying are discussed.

Apple, Mite Control, 1987

Abstract Test chemicals were applied to 10- to 31-yr-old apple trees at Monmouth, Maine, as dilute sprays using a handgun and a hydraulic sprayer operating at 250 psi and at 325-350 (Tests 1 and 2) to 375-400 gal/acre. Spray dates were 16 May (full pink), 29 May (petal fall), 12- 17 Jun (first cover) and 16 Jul (third cover). The standard pesticide program consisted of Difolatan 80 Sprill (8 lb/100) on 16 Apr (the only cover pesticide applied in Test 4), Captan 80W (1 lb) on 6-9 dates, Manzate 200 80W (1.5 lb) and Sevin 80S (1-1.2 lb) on 2 dates, and Pydrin 2.4EC (2.7 oz) on 4 dates. There were no mixtures of acaricides with other pesticides. There were 4 single-tree replications for each treatment. A randomized complete block design was used, with 2 'Red Delicious' and 2 'Cortland' cultivars in Tests 1 and 3, 3 'Red Delicious' and 1 'Cortland' in Test 2, and 4 'Cortland' in Test 4. From each tree 25 leaves were collected at chest height around the periphery of the tree, brought into the laboratory, and brushed onto glass plates coated with a Tween 20 and alcohol mixture; mites were counted the same day. May, June, July, and August were generally warmer than normal; all except June were relatively dry. Of special note were 94°F maximum temperatures recorded 1 and 2 days after the petal fall spray (Test 2).

Apple, Insect Control, Hudson Valley, Highland, New York, 1984

Abstract Treatments were applied to 8-tree plots replicated 3 times in a randomized complete block design. Treatments were applied at pink, 7 May, petal fall, 3 or 4 Jun, and in cover sprays 18 Jun, 2 Jul, 16 Jul, 30 Jul, and 15 or 16 Aug. The 2 Dimilin treatments were applied 7 May, 2 Jul, and 16 Jul; the DPX Y5893 treatments 7 May; and the Spur treatment on 7 May, 4 Jun, 2 Jul, and 30 Jul. Guthion was applied to the Dimilin and DPX plots on the remaining dates. Pounce was applied 7 May and 4 Jun, while Advantage was applied on the remaining dates. Treatments were applied to runoff using a high-pressure handgun sprayer at 400 psi delivering 4.2 gal spray/tree or 403 gal/ acre. Trees were 20-years-old, 12 ft high, spaced 15 by 30 ft, and on EMU rootstock. Additional applications over the entire block included: Bravo 500 8 qt/ acre, 18 Apr; Captan 50WP 3 lb/acre, 4 Jun and 28 Jun; Vangard 10WP 30 oz/acre, 28 Jun; Benlate 50WP 1 lb/acre, 13 Jul; and Dithane M-45 78WP 6 lb/ acre, 26 Jul and 15 Aug. Plictran 50WPP6 oz/100 gal, was applied for mite control in the Pounce and Dimilin/Guthion plots on 26 Jul. AA were evaluated on 1 ‘Rhode Island Greening’ tree/plot on 20 Jul; RAA on 1 ‘Cortland’ tree/plot on 8 Jun; EAS from 1 ‘McIntosh’ tree/plot on 12 Jun; and STLM on 1 ‘Empire’ tree/plot on 17 Oct. Insect damage to fruit was assessed at harvest by examining 100 fruits/cultivar/plot from ‘McIntosh’ 10 Sep, ‘Empire’ 24 Sep, and ‘Golden Delicious’ 4 Oct. A cool, wet spring resulted in bloom lasting longer than normal. Continual rainfall during the final week of bloom prevented timely application of the petal fall spray.

A NEW APPROACH TO SAN JOSE SCALE CONTROL (HEMIPTERA: DIASPIDIDAE)

AbstractA laboratory experiment demonstrated that in San Jose scale, Quadraspidiotus perniciosus (Comstock), the male is susceptible to a number of insecticides. Diazinon was the most effective as it killed the males before they emerged from their shells. Males emerged and survived for a short time before being killed by residues of azinphosmethyl and endosulfan. In an orchard, a petal fall spray of diazinon or Penncap E applied when male scales started to emerge gave good control of San Jose scale and was as effective as three summer sprays of diazinon timed to emergence of crawlers. Penncap E was ineffective against the crawlers. Post-bloom sprays are necessary to control infestations of incrusted scale because a pre-bloom oil application usually fails to contact live scale that may be underneath one or more layers of old dead scale.

Pear, Pear Psylla Seasonal Control, 1976

Abstract Seven seasonal insecticide programs were applied with a Myers speed sprayer to 2 pear blocks containing Bartlett, Bosc, Gorham, and Clapp Favorite cultivars. Each program except that evaluating MO 9087 which was replicated only once, was replicated 3 times. All plots were ca 1 acre and arranged in a randomized complete block design. Sprays were applied on March 29, April 9, April 29, May 24, June 30, July 20 and August 9. All were dilute (IX) except the petal fall spray on May 24 which was applied 3X. Nymphs were sampled on May 17, June 29, and July 26 by putting 10 spurs from each of 4 trees/replication into a Berlese funnel. Adults were sampled by searching for 2 minutes on 4 trees in each plot on August 9 before the final spray application.

Integrated Control of the Fruit-Tree Leaf Roller and the White Apple Leafhopper in British Columbia123

Azinphosmethyl, diazinon, or parathion applied at the pinkbud stage ‘McIntosh’ apple, and DDT applied at the petal-fall stage gave good control of the fruit-tree leaf roller, Archips argyrospilus (Walker), on McIntosh, ‘Delirious,’ and ‘Spartan’ apple trees. Dormant oil-ethion at the 1/2-inch green stage and endosulfan at the petal-fall stage were less effective and aldicarb as a soil treatment was ineffective. DDT and endosulfan as pedal-fall sprays gave excellent control of the white apple leafhopper, Typhlocyba pomaria McAtee. A pink-bud spray of azinphosmethyl, diazinon, or parathion and a petal-fall spray of endosuIfan could be used in conjunction with a sterile-codling moth pro!(ram to control fruit-tree leaf roller and white apple leafhopper. In addition, the above materials and timing of sprays did not affect either phytophagous or predator mites.

Chemical Thinning of Apple Trees Using Concentrate Sprays1

Abstract Sevin was used in thinning sprays in dilute—1x—and concentrate form—ranging from 3X to 33X —over a 4-year period on mature ‘Rome Beauty’ apple trees. Although treatments were not the same in each year, all sprays applied significantly thinned in 3 out of 4 years. There was some evidence that concentrate sprays thinned less than dilute sprays, but usually not significantly so. When using 33X concentrates, significant thinning was achieved in 1 year when Sevin was used at full strength—33 lb./100 gal. Approximately the same degree of thinning was obtained when the rate was reduced by one-half. Adding pesticides commonly used in petal-fall sprays to Sevin—all concentrated to the same extent—did not alter significantly the thinning obtained with Sevin alone. Results on ‘Jonathan’ apples in a 1-year experiment revealed significant thinning with NAD and Sevin in a dilute spray, as well as Sevin at 3X and 6X concentrates. In a 1-year experiment on ‘Golden Delicious’, NAA thinned significantly as a dilute spray, and at 3X and 6X concentrates. The dilute spray was more effective.

Field Trials With Lead Arsenate For the Control of Codling Moth,Cydia Pomonella(L.), on Apple

Trials were carried out at East Mailing from 1960 to 1962 to assess the efficiences against codling moth of spray programmes comprising high- volume applications of o∙2% lead arsenate. A programme of two sprays applied three weeks apart, the first application being made about ten days after larvae began to hatch, was used as a standard in each trial.The addition of a petal-fall spray to the standard programme resulted in better control, particularly of calyx entries, total damage being reduced in three trials by 76%, 85%, and 93% as compared with 65%, 63%, and 57% respectively. Three sprays applied at fortnightly intervals from the beginning of the hatching period also gave better control than the standard programme, reducing damage by 80% as compared with 56%. A programme of two sprays, the first applied at the beginning of the hatching period and the second three weeks later, appeared to give poorer control than the standard in one trial and better control in another, but the difference was not signific...

Control of the Grape Mealybug on Apricots

The grape mealybug, Pseudococcus maritimus (Ehrh.), is a relatively new pest of apricots. This pest damages the fruit by colonizing in the stem end. The honeydew produced by the insects discolors the fruit and cannot be removed. The mealybug overwinters as crawlers within egg masses laid in cracks in the bark or in other protected places. The crawlers emerge in early spring and feed at the base of new shoots. A second generation develops by June, and crawlers of this generation infest the fruit. After harvest, mature females lay eggs that hatch by late fall. The young mealybugs remain within these cottony egg masses during the winter. Experimental plots during the 1957-58 season showed that treatments timed to the spring emergence of crawlers were effective and were preferred to fall or winter sprays. Of the materials tested, parathion and Diazinon® ( O,O -diethy1 O -(2-isopropyl-4- methyl-6-pyrimidinyl) phosphorothioate) provided the best control. In 1959 pink bud and petal fall sprays gave better control than those applied during June, by which time some fruits were already infested. As in 1958, parathion and Diazinon were the most effective insecticides.

Results of Spraying and Dusting Experiments on Large Blocks Of Peach Trees for the Control of The Curculio

Blocks of peach trees 26 by 26 rows each were used for these experiments to determine the comparative effectiveness of spraying and dusting and to test the value of the “petal-fall” application. Lead arsenate applied as a spray was found to be more effective against the curculio ( Conotrachelus nenuphar Herbst) attacking peaches than the same insecticide applied in ll. dust mixture. The petal-fall spray, applied when 50 to 75 per cent of the petals had fallen, was shown to be an important part of the spray schedule.

The Plum Curculio Outbreak in the Charlottesvillecrozet Section of Virginia In 1929

An attempt is made to explain the heavy losses from curculio in the Charlottesville- Crozet section. It is believed that the important factors were omission of the petal-fall spray, lack of thorough cultivation, and heavy rainfall in the early season.

Red Bug Control in Southern Pennsylvania

The hatching period of the bright red bug, Lygidea mendax, in southern Pennsylvania comes so late in the blossom pink stage of nearly all varieties of apples that the pink spray is ineffective in control. A comparison of pink with the petal fall spray on the York Imperial, a late blooming variety, gave little difference in control. Two applications of nicotine gave no additional control. On earlier blooming varieties the petal fall spray would prove much more effective. One application of nicotine at petal fall is advised.