White Bud Research Articles

Pear, Evaluation of Dimilin For Pear Psylla Control, 1986

Abstract The trial was conducted in a 3 acre block of ‘Bartlett’ pears near Biglerville, PA. Six trees were randomly chosen in the block for monitoring. Three trees at the edge of the block were left untreated and served as controls. Chemicals were applied as a complete spray to both sides of trees with a Bean airblast sprayer calibrated to deliver 50 gal/acre. Application dates and rates were as follows: 1 Apr—bud burst (Dimilin 25WP 454 g plus 60 sec. oil 10.1 liters/acre), 14 Apr—white bud (Dimilin 25WP 454 g plus Manzate 200 1.2 Kg/acre). When PP populations on control trees reached damaging levels, they were treated with a handgun to the point of runoff. Application dates and rates for control trees were as follows: 9 May (Pydrin 2.4EC 118 ml plus Mitac 1.5EC 473ml/100 gals), and 23 May (Thiodan 50WP 454 g plus Mitac 1.5EC 946 ml/100 gals). Treatments were evaluated for PP control by counts of eggs and nymphs at 1 to 2 week intervals. Counts were made by sampling 10 spur or mid-terminal leaves per tree. PP pressure was heavy.

Pear: Early Season Pear Psylla Control, 1985

Abstract Experimental sprays were applied to non-replicated 0.4-acre plots consisting of cultivars Bartlett, Anjou, and Bosc (7 yr old). Treatments were applied with a handgun from a truck-mounted hydraulic sprayer at 375 psi. Dates of application were: white bud (18 Apr) and petal fall (1 May). Treatments were evaluated for pear psylla control by counts of eggs and nymphs at 1 to 2-wk intervals on the cultivar Bartlett. Counts were made by sampling 10 mid-terminal or spur leaves from 4 trees randomly selected in each plot. Pear psylla pressure was heavy throughout the experiment.

Pear, Full Season Insecticide Test, 1985

Abstract Treatments consisted of unreplicated 0.19-acre blocks. Materials were applied by airblast sprayer in 116 gpa. Alsystin and F4999 were applied on 22 Apr (green tip), 26 Apr (tight cluster), 2 May (white bud), 9 May (petal fall = PF), 24 May, 7 Jun, 24 Jun, 8 Jul, 22 Jul, 7 Aug and 21 Aug. Mitac was applied on 9 May (PF), 8 Jul, 7 Aug and 21 Aug. All other materials were applied on 9 May, 24 May, 7 Jun, 24 Jun, 8 Jul, 22 Jul, 7 Aug and 21 Aug. On each sample date 50 leaves were randomly sampled from each of 4 centrally located trees in each block. A subsample of 25 leaves were examined for psylla nymphs using a stereo microscope. All 50 leaves were then brushed in a mite brushing machine and numbers of RM recorded for 8 sections. For broad spectrum pests 50 fruit were sampled from the 4 sample trees and examined for insect damage. Damages were categorized by their respective pest.

Control of Spruce Gall Midge in Southern ct 1983

Abstract Nine insecticides were evaluated for control of spruce gall midge in commercial plantations of white spruce 1 to 2 m tall. Applications were made in either late Apr or early May, or at both times, in a randomized block experiment with 4 replications at Guilford and five at Middlefield. Insecticides at the rate of 1 lb (AI)/100 gal were applied to runoff with a Solo knapsack sprayer. The Apr treatment was applied when white spruce buds were swelling and bud scales were separating, and when adult midges were emerging and beginning to lay eggs; the May application was made when new shoots had elongated 1 to 2 cm. Infestation was rated 0 to 5: 0, no visible infestation; 1, very light visible infestation; 2, light infestation with some swollen shoots; 3, moderate infestation with noticeable swollen and stunted shoots; 4, severe infestation with many swollen, stunted shoots and some dead needles and shoots; 5, very severe infestation with many swollen, stunted and deformed shoots and abundant dead needles and shoots. Infestation on 1982 shoots was rated before treatment and only trees with a rating of at least 1 were treated.

Characteristics of the Stigma of Chickpea1

Breeding advancements in the chickpea, Cicer arietinum L. have been hampered by limited success in cross‐pollination attempts. This study was undertaken to examine the characteristics of the stigma microscopically and histochemically to determine the period of maximum receptivity. The high degree of self‐pollination in the chickpea is attributed to the fact that flowers are autogamous and that only certain papillate cells of the stigma are specialized to receive pollen when it is shed prior to full flower bloom. During the white bud stage, such specialized cells produce a localized secretion which reacts positively to an esterase test. This test detects stigmatic surface proteins which are believed to be functionally important in the retention and hydration of pollen grains and, possibly indicates the site of the stigma‐pollen compatibility reaction. These observations suggest that the low success rate of artificial hybridizations in chick‐pea may be related to the timing of stigma receptivity and to the limited number of cells on the stigmatic surface which appear to be receptive to pollen. Functional specialization of stigmatic cells has not been reported in other legumes, and may be unique among crop plants.

Regulation of Cropping and Fruit Quality of Conference Pear by the Use of Gibberellic Acid and Thinning. II. The Effect of Ethephon as a Flower Thinner When Used in Conjunction with Gibberellic Acid Application

SummaryThe number of fruits developing on Conference pear trees treated at flowering with gibberellic acid was reduced by the application of ethephon, and the amount of large fruit increased. Although time of application, from white bud (pre-GA3) to petal-fall, did not influence the response to ethephon, both temperature and the concentration of GA3 affected the response considerably. Although increasing the alkalinity of an aqueous ethephon solution compensated for low temperatures, in terms of the amount of ethylene released into an enclosed space, the result of using this technique with a field spray was inconclusive. The mechanism of action of ethephon as an abscission agent in relation to its breakdown characteristics is discussed.

A Morphological Study of the Development of Reproductive Structures of Phaseolus lunatus L.1

Abstract Lima bean, Phaseolus lunatus cv. Early Thorogreen, is primarily self-pollinated. Morphological characteristics of reproductive structures which facilitate self-pollination include the stage of floral development at the time of anther dehiscence and the relative positions of anthers and stigma within the keel at the time of pollen shedding. Coincidental maturation of pollen and receptivity of the stigmatic surface also enhance the capacity for self-pollination. The varying degrees of cross-pollination frequently reported may be facilitated by extrusion of the stigma from the keel, which occurs in connection with insect visitation at an thesis, and also by the prolonged period of stigma receptivity, which extends from the white bud stage through anthesis.

Pear, Pear Psylla Control, 1977

Abstract A three-year-old pear block was divided into eight tree plots replicated three times in a randomized complete block design. The Morestan treatment was first applied at the white bud stage April 19. The two Ambush treatments were applied June 9 but 2.2 in. of rain fell before these treatments dried. All seven treatments were applied or reapplied on June 13. Treatments were applied dilute to runoff with high pressure handgun sprayer at 425 psi using ca 1.2 gal per tree (225 gal/acre). Treatments were evaluated by sampling four spurs per plot and counting all pear psylla nymphs and eggs on each spur under a binocular scope in the laboratory. The pre-treatment count on June 8 indicated a good 2nd brood nymphal population was present. Post-treatment counts were made June 17 and July 11.

Effects of Ethephon on Seed Yield of Phaseolus vulgaris L.1

Abstract No significant differences in bean seed yield of field grown ‘Dark Red Kidney’ beans were observed in plants treated at the green or white bud stage or in full bloom with (2-chloroethyl)phosphonic acid (ethephon) at concentrations ranging from 300 to 2400 ppm. Plants treated with 300 and 600 ppm ethephon produced and retained more flowers and matured 7-10 days earlier than untreated plants. Treatment with 1200 and 2400 ppm reduced flower production and delayed pod maturity.

Further Trials on Alternatives to DDT for the Control of Pre‐blossom Pests on Apple and Pear

SUMMARYBetween 1967 and 1970, 19 insecticides in nine trials in southern and eastern England were evaluated for the control of pre‐blossom pests on apple. Where sprays were applied at the green‐cluster stage, azinphos‐ methyl, dichlorvos, ‘Dursban’, fenitrothion, methidathion and phos‐ alone gave an equivalent or better control than DDT of winter moth larvae, tortricid larvae and apple capsid. Iodofenphos, phosmet and trichlorphon were also as effective as DDT against tortricid larvae and apple capsid but gave more variable control of winter moth larvae. Carbaryl, Ciba C11042, cyanophos, monocrotophos and pirimiphos‐methyl in single trials and Du Pont 1642 and ‘Torak’ also gave effective control of winter moth and tortricid larvae; no data were available on their effect on apple capsid.Dichlorvos, ‘Dursban’. fenitrothion, methidathion and phosmet were particularly effective against apple sucker. Cyanophos, Du Pont 1642, iodofenphos, monocrotophos and ‘Torak’ were also effective in single trials, but azinphos‐methyl, phosalone and trichlorphon gave less effective control of apple sucker when infestations were heavy.In one trial, azinphos‐methyl, dimethoate and fenitrothion effectively controlled apple‐grass aphid. Where a bud‐burst spray was applied, azinphos‐methyl, DDT, Du Pont 1642,‘Dursban’ and iodofenphos in a single trial all gave some control of apple blossom weevil. Although green‐cluster sprays are generally too late to prevent some damage by apple blossom weevil, some degree of control of larvae was achieved at that stage by azinphos‐methyl, Ciba C11042, Du Pont 1642, pirimiphos‐methyl and ‘Torak’.In a single trial on pear, azinphos‐methyl or phosalone applied at green cluster or white bud, or methidathion at green cluster, gave a control of winter moth larvae equivalent to DDT.

Frost Damage to White Spruce Buds

Unopened buds of white spruce (Piceaglauca (Moench) Voss) were damaged by late spring frost. At time of death of the apical meristem the buds were not ready for flushing. As expected on the basis of ground frosts, there was more damage among shorter trees than among taller trees, and more damage among open-grown trees than among understory trees.

CONTROL OF THE PEAR RUST MITE, EPITRIMERUS PYRI (ACARINA: ERIOPHYIDAE)

AbstractMorestan applied at the white bud, calyx, or white bud plus calyx stage on Bartlett pears gave good control of the pear rust mite, Epitrimerus pyri (Nal.), and prevented fruit russet caused by rust mite feeding. A June spray of Morestan or ethion also controlled the mite but did not prevent fruit russet. During the white bud and calyx stage, the rust mite is found at the base of leaves and flowers but moves to the fruit shortly after the calyx stage. By early June, it can cause considerable fruit russet, especially on the calyx end of the pears.

CONE CROPS OF WHITE AND BLACK SPRUCE ARE PREDICTABLE

In the spring of 1963 an experiment was initiated to find ways of predicting seed crops of white and black spruce in the Interior of British Columbia. Morphology and anatomy of the buds were studied. Initiation of reproductive buds of both species started in late July. Positive identification of the buds at this stage of development required dissection under low magnification. By late August, reproductive buds of white spruce and male buds of black spruce could be distinguished macroscopically by their size and shape. It was difficult to distinguish between white spruce male and female buds and, between black spruce female and vegetative buds in the fall without dissection.

Red Squirrel Damage to Coniferous Plantations and Its Relation to Changing Food Habits

For several years a winter injury of unknown cause had been noticed in central Massachusetts coniferous planatations by members of the Harvard Forest staff. Twigs were cut off as cleanly as though by a knife, and in sufficient quantities to cause real damage to the trees. During the winter of I924-25. a study of the injury was made. To find the cause of the damage, several plantations were watched during early winter until, with the first heavy fall of snow, the clipping began. Then a plantation of Scotch pine (Pinus silvestris) where the activity appeared to be greatest, was watched from a blind until a red squirrel, Sciurus hudsonicus loquax Bangs I was seen doing the cutting. A study of the squirrel's habits here made it possible to identify him as the cause of all other fresh work found. He was also later seen eating European larch (Larix europaea) and white pine (Pinus strobus) buds. The next objective was to find out from the forester's standpoint how serious the injuries were. The damage takes place only when it is difficult or impossible for the squirrel to find food on the ground. A period of warm weather following such a time and resulting in the thinning of the snow to a few inches in depth greatly reduces the amount of damage per day. An exception to this general statement is that European larch and white pine buds, at least, are eaten when they are just beginning to swell in the spring. Scotch pine, Norway spruce (Picea Abies) and European larch are heavily injured. Only one red pine (Pinus resinosa) was found damaged out of hundreds examined. White pine is ordinarily immune, but in a winter of deep snow a heavy leader injury takes place. Often a group of young trees will be over ninety per cent injured, and in one case trees up to 25 feet tall lost their terminals. Red spruce (Picea rubens) is apparently ignored entirely. It was thought that white spruce (Picea canadensis), a species introduced from further north, but which grows vigorously in northern Massachusetts, would be strongly attacked. Examination of several hundred trees in a i9 year old plantation showed only one injury per hundred, while a nearby stand of Norway spruce was heavily damaged. Besides the region where the study was made, the author has found the injury in northeastern Massachusetts, northern Connecticut and central New York. So it is by no means local, and probably occurs throughout the range