Chemical Defoliation Research Articles

Further studies on chemical defoliation of deciduous nursery plants

In experiments with cultivars of apple, pear, plum (European and Japanese), peach, almond, apricot, and cherry the defoliation effects were measured of concentrations of potassium iodide (KI), bromodine, DEF (S,S,S-tributylphosphorotrithioate) and a bromodine/ethephon ((2-chlorethyl) phosphonic acid) mixture, applied as either single or double sprays. Double sprays and higher concentrations were more effective than single sprays and lower concentrations but the most effective chemical differed between species. In further experiments the effects were measured of pre-spraying with the growth retardant SADH (succinic acid -2, 2-dimethylhydrazide) or the auxin transport inhibitor TlBA (235-triiodobenzoic acid) followed by selected defoliants. Pre-spraying with SADH followed by either potassium iodide or bromodine significantly increased leaf fall on apricot but not Japanese plum or almond. Pre-spraying with TIBA followed by ethephon or DEF significantly increased leaf fall on apple and almond but not pear or apricot.

Chemical Defoliation of Young, Budded Pecan Trees1

Abstract Applications of ethephon, ethephon plus KI, ethephon plus HI, ametryne and VCS-438 in Oct. promoted good to excellent leaf abscission on young, budded pecan trees (Carya illinoensis Koch). Combinations of ethephon and KI caused greater leaf abscission than either material alone. Complete defoliation of the trees in 4 weeks was obtained with ametryne in both 1970 and 1971. Only paraquat affected bud break and growth of young trees the next spring. Patterns of leaf abscission resulting from various chemical treatments support the concept that factors in addition to ethylene are involved in pecan defoliation.

Chemical defoliation of deciduous nursery plants

Peach seedlings were pre-sprayed with the growth retardant SADH (Succinic acid-2,2-dimethylhydrazide) at nil, 2000 or 4000 p.p.m. followed by one or two applications of the defoliant ethephon . ((2-chloroethyl) phosphonic acid) in either March or April at nil, 100, 200, 300, or 500 p.p.m. Leaf drop was increased by SADH and ethephon. Two applications of ethephon were better than one and April sprays were better than March sprays. Phytotoxic effects occurred with ethephon at 500 p.p.m. In a second experiment cultivars of a range of species were sprayed with the defoliants ethephon and DEF (S,S,S-tributylphosphorotrithioate) at various concentrations. In general DEF was the more promising chemical with good results on apples, pears and cherries. Neither compound was successful for peaches, apricots and Japanese plums.

Avoiding Secondary Leaf Fall Disease of Rubber by Chemical Defoliation

(1971). Avoiding Secondary Leaf Fall Disease of Rubber by Chemical Defoliation. PANS Pest Articles & News Summaries: Vol. 17, No. 4, pp. 461-463.

Inheritance of Resistance to Chemical Defoliation in American Upland Cotton, Gossypium hirsutum L.1

Data from S1, F1, F2, and BC1 populations treated with the defoliant, Def, indicated that resistance to chemical defoliation in Upland cotton, Gossypium hirsutum L., was controlled at a single locus. The symbol df was assigned to the gene in question. Two phenotypes were recognized in the F2 in the ratio of 3 susceptible (Df—): 1 resistant to chemical defoliation (dfdf).

Defoliation of Vitis Vinifera Grapevines by Artificial Means

Chemical defoliants, desiccants, and mechanical aids were tested at different stages of grapevine development. Effective in defoliating the grapevines was flaming followed by removal of the dried leaves with a stream of water. Flaming left no residue that could contaminate the berries. Most chemical treatments were unsuccessful, primarily because of damage to the clusters. The best chemical treatments were no better than flaming.

The Effect of Chemical Defoliation on the Development of Apple Spurs

An analysis was made of bud development on apple spurs sprayed with copper sulphate in late spring. The treatments caused the spur buds to break into a second flush of growth and eventually to form a new resting bud. The failure of these later buds to become fruit buds was correlated with the time in the season when they began to form, and was determined by the number of leaves and bud scales preceding the buds. The number of leaves in the second flush was related to the extent to which shoot tips and spurs were killed by the sprays; the number of leaves in the first flush and the number of bud-scales between these flushes of growth was also altered by the chemical. The factors affecting the number of nodes in each of these zones of growth are discussed, and it is suggested the sprays reduced the level of endogenous auxins in the leaves and endogenous gibberellins in the shoot tips. Differences associated with the vigour of the trees and with seasonal factors were also observed. The difficulties in estimating these factors limit the commercial value of this technique.

Use of Chemical Defoliants on Peach Trees in Integrated Program to Suppress Populations of Green Peach Aphids123

When peach trees were sprayed with chemical defoliants to control green peach aphids, Myzus persicae (Sulzer), the number of aphids per leaf was higher on leaves remaining on the sprayed trees, but the number of aphids per tree was higher on the unsprayed trees. The high density of aphids per leaf in the foliage still present on sprayed trees was associated with an increase in deposition of syrphid eggs per leaf. Also, the number of aphid eggs was significantly fewer on the sprayed trees than on the unsprayed trees. The decrease in deposition of aphid eggs in 1966 compared with 1965 was correlated with the differences in trends of aphid population, temperatures, and syrphid activities.

The Reproduction-Diapause Approach to Population Control of the Boll Weevil123

Six applications of a spray of methyl parathion (0.5 lb per acre) were made at 4- to 5-day intervals to isolated cotton fields in Carroll County, Mississippi, to control reproducing and diapausing boll weevils, Anthonomus grandis Boheman, during the fall. The most effective follow up procedure included chemical defoliation of cotton plants to limit the available weevil food, and a final application in October of Bidrin® (3-hydroxy- N, N -dimethyl- cis -crotonamide dimethyl phosphate) at 1 lb per acre. Examination of seedling cotton from the treated fields the following spring indicated that in 1 field only 2.7 weevils per acre had survived the control program and the winter weather. The boll weevil population in the treated fields did not rise to damaging proportions until mid-August (the 2nd generation).

Preliminary Studies on Yield, Earliness and Boll Weight by the use of Chemical Defoliants on MCU. 1 Cotton

The effect of chemical defoliants on the yield, carliness and boll weight of MCU. 1 cotton is reported in this article.

Timing of Defoliants and Desiccants to Reduce Populations of the Pink Bollworm in Diapause1

Diapause in the pink bollworm, Pectinophora gossypiella (Saunders), is under photoperiodic control and does not generally occur in populations near College Station, Texas, until mid-September. The termination of growth of cotton plants with chemical defoliants or desiccants before this date caused a reduction of almost 90% in the number of diapause larvae. Defoliation or desiccation of plants in early October, when most of the larvae were in diapause, was not nearly so effective in reducing the potential overwintering population as the earlier application. Results emphasized the importance of early maturity and early defoliation or desiccation of infested fields.

Chemical Defoliation of Cotton VII. Effectiveness of Adjuvants Under Several Specific Plant and Environmental Conditions1

SynopsisThe use of adjuvants with chemical defoliants increased the amount of leaf fall and rapidity of defoliation under limiting conditions such as wilted, toughened and inactive leaves, immature leaves and bolls, low temperatures, and conditions due to excessive applications of nitrogen. Under conditions considered favorable for defoliation, the use of adjuvants with chemical defoliants hastened leaf fall but no significant increase in total leaf fall was evident. The use of adjuvants with chemical defoliants did not retard defoliation.

The Effects of a chemical Defoliant on an isolated Tsetse Fly Community and its Vegetation

SummaryThree aerial applications of the n-butyl ester of 2,4,5-trichlorophenoxyacetic m acid (2,4,5-T) in diesel oil were made at intervals of six weeks to an isolated woodland community on a peninsula in Lake Victoria, Kenya. The woodland contained two species of tsetse fly, Glossina pallidipes Aust. and G. palpalis (R.-D.) (subsp. fuscipes Newst.). The object of the treatment was to defoliate the woodland in order to ascertain whether the reduction in shade would control the tsetse fly. It was also desired to obtain further information on the effect of the spray applications on the woody plant species.The first application, at an estimated actual dosage of 2·2 lb. 2,4,5·T per acre, resulted in a rapid defoliation of 13 out of the 15 observed leafy species, eight of, which subsequently died during the following nine months. Two succulent species of Euphorbia also died during this period. Of the remaining two species, one was fully defoliated only after the third application but recovered slowly, while the other, Lecaniodiscus vaughaniae, was but slightly affected at any time.No significant reduction in the numbers of tsetse fly was observed during the nine-month period following the first spraying. The following factors probably account for this lack of effect: the varying rate of defoliation of the different plant species, the resistance to the spray of one locally abundant species, the persistent shade cast by the stems of the thick vegetation after defoliation and the relatively humid climate during the period of maximum defoliation. These factors allowed an environment favourable for the tsetse fly to exist in one part or another of the peninsula in spite of the severe effects on the vegetation.Nine months after the first spraying, between a third and a half of the vegetation was destroyed during the dry season by an accidental fire. The effect on G. pallidipes was almost immediate, and two months later the population had been reduced to a fairly low level, which was maintained for the last 16 months of the experiment. The fire hardly affected the environment of G. palpalis and the main effect of defoliation was to cause this species to concentrate near the shady lake shore, where the dominant tree was Lecaniodiscus vaughaniae.There is little doubt that the destruction of the vegetation by fire was made possible by the effects of the spray applications, as the hitherto evergreen thicket would normally have been unburnable. While this suggests a possible new technique for bush clearance, further trials have indicated several factors which may make difficult a satisfactory burn following defoliation.Details are given of the assessment of the spray droplet performance both in calibration trials and during the applications to the peninsula.

Chemical Defoliation of Cotton: VI. Defoliation as Effected by Chemical Applications to the Soil1

SynopsisCotton defoliation was not effected when any of several defoliant‐type chemicals were applied to the soil. Difficulties associated with the commercial aspects of applying defoliants in irrigation water are discussed.

Chemical Defoliation of Cotton: V. Effects of Premature Defoliant and Desiccant Treatments on Boll Components, Fiber Properties, Germination, and Yield of Cotton1

SynopsisChemical defoliant and desiccant treatments of cotton in Arizona when bolls were less than 35 days of age adversely affected boll components, fiber length, percent germination, and yield. No damage was found when bolls were 35 or more days of age.

Chemical Defoliation of Cotton IV. Lodging in Bottom Defoliated Cotton1

Chemical Defoliation of Cotton IV. Lodging in Bottom Defoliated Cotton¹

Chemical Defoliation of Cotton: III. A Study of Seed and Fiber from Cotton Plants Treated with Amino Triazole1

Agronomy JournalVolume 46, Issue 12 p. 580-581 Note Chemical Defoliation of Cotton: III. A Study of Seed and Fiber from Cotton Plants Treated with Amino Triazole1 Lamar C. Brown, Lamar C. Brown Plant Physiologist and Agronomist, respectively, Field Crops Research Branch, A.R.S., U. S. Dept. of Agriculture, U. S. Field Station, Sacaton, Ariz.Search for more papers by this authorAngus H. Hyer, Angus H. Hyer Plant Physiologist and Agronomist, respectively, Field Crops Research Branch, A.R.S., U. S. Dept. of Agriculture, U. S. Field Station, Sacaton, Ariz.Search for more papers by this author Lamar C. Brown, Lamar C. Brown Plant Physiologist and Agronomist, respectively, Field Crops Research Branch, A.R.S., U. S. Dept. of Agriculture, U. S. Field Station, Sacaton, Ariz.Search for more papers by this authorAngus H. Hyer, Angus H. Hyer Plant Physiologist and Agronomist, respectively, Field Crops Research Branch, A.R.S., U. S. Dept. of Agriculture, U. S. Field Station, Sacaton, Ariz.Search for more papers by this author First published: 01 December 1954 https://doi.org/10.2134/agronj1954.00021962004600120012x 1 Acknowledgment is due to the American Cyanamid Co. and the American Chemical Paint Co. for supplying the amino triazole, and to the American Cyanamid Co. for supplying the AERO Cyanamid Soluble Defoliant used in these studies. The writers also express their appreciation to Lily L. Ramsey for assistance with the fiber tests. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume46, Issue12December 1954Pages 580-581 RelatedInformation

Chemical Defoliation of Cotton

Chemical Defoliation of Cotton

Influence of chemical defoliation upon the boll-opening in cotton : 1. Effect of chemical treatment on the boll-opening

In this study, we have examined the influence of spray with several solutions of lime, nitrogen and potassium chlolate on the boll-opening in cotton. Results obtained are as follows ; (1) The chemical injury of leaves was very serious, resulting in almost complete defoliation about two weeks after the treatment. On the other hand, the boll-shedding increased slightly though the symptom of injury on capsules was scarcely recognized. (2) The boll-opening was accelerated fairly especially at l0 to 15 days after the treatment, but on the contrary, checked afterwards. (3) In general, but that the amounts of yield in treated plots were much in early stages and lessened in later one, of seed cotton were not significantly different form that in the control plot. (4) The influence of treatment upon lint percentage and length of fibers was not recognized, but on the weight of seed cotton per boll and strength of fibers, some differences were recognized and the strongly treated plots were inferior to the control.

The effect of applied sugars light intensity, and temperature upon the chemical defoliation of cotton.

The effect of applied sugars light intensity, and temperature upon the chemical defoliation of cotton.