Double Sprays Research Articles

Productivity and Econometric Analysis of Leguminous Monkey-nut (Arachis hypogaea L.) as Influenced by Growth Retardant

Background: Groundnut (Arachis hypogaea L.) holds significant importance as a staple food legume and a key economic crop, serving as a valuable source of edible oil and protein in India. However, its full yield potential is often hampered by excessive vegetative growth, which leads to suboptimal yields. With this background, a field experiment was conducted at the Perunthalaivar Kamaraj Krishi Vigyan Kendra in Puducherry during 2020 and 2021. The objective was to investigate the influence of different concentrations and timing of paclobutrazol (PBZ) application on the growth and yield of groundnut. Methods: The experiment was laid out in a split-plot design with three replications, six main plot treatments (Including PBZ concentrations of 25, 50, 100, 150, 200 ppm and a control) and three sub-plot treatments (Involving single sprays at 30 days after emergence (DAE), single sprays at 50 DAE and double sprays at 30 and 50 DAE). Result: The results revealed that the application of paclobutrazol at different concentrations had a positive effect on reducing plant height during the later stages of growth, particularly when a double spray was applied at 30 and 50 DAE. Notably, the application of paclobutrazol at a concentration of 200 ppm in groundnut cultivation proved to be economically viable, resulting 29% increase in pod yield compared to the control group. Specifically, PBZ at 200 ppm, with a double spray, significantly boosted the total pod yield to 2724 kg ha-1. Furthermore, the correlation and regression analyses indicated a positive relationship between growth and yield.

Chemical Composition and Insecticidal Potential of Six Essential Oils from Morocco against Dactylopius opuntiae (Cockerell) under Field and Laboratory Conditions.

Simple SummaryThe prickly pear Opuntia ficus-indica L. has an important economic role as a source of food for human consumption, for cosmetic and pharmaceutical purposes, and as fodder for livestock in Morocco. This crop is now attacked by a new sap-sucking insect pest, the wild-scale Dactylopius opuntiae (Cockerell). The aim of this study was to investigate the insecticidal potential of essential oils as alternative to synthetic insecticides for the control of D. opuntiae nymphs and adult females under laboratory and field conditions. Results revealed that Mentha pulegium and Origanum vulgare oils provided a rich source of bioactive compounds and exhibited high contact toxicity against D. opuntiae. In addition, M. pulegium and O. vulgaris oils applied in combination with black soap induced the highest toxic activity on adult females under field conditions.The carmine cochineal Dactylopius opuntiae (Cockerell) is the major insect pest of the prickly-pear cactus Opuntia ficus-indica (L.) in Morocco. The present study investigated the insecticidal activities of six essential oils (EOs) against nymphs and adult females of D. opuntiae applied singly or in combination with a detergent under laboratory and field conditions. Under laboratory conditions, M. pulegium and O. vulgare L. essential oils showed a high level of insecticidal activity at 5%, with 98% and 92% females’ mortality, respectively, 5 days after treatments. The M. pulegium and O. vulgaris oils at 5% applied in combination with black soap at (60 g/L) induced the highest toxic activity on adult females, 100% and 96% at 5 days after treatments, respectively. Under field conditions, M. pulegium and O. vulgare oils at 5% in combination with black soap (60 g/L) showed the highest adult female mortalities with 96.33 and 92.56%, respectively, 7 days after the first application. The double application of M. pulegium oil at 5% significantly increased the mortality of adult females up to 91%, 5 days after the second spray. GC-MS analysis revealed that the most abundant constituent of M. pulegium and O. vulgare oils was pulegone (84.69%) and durenol (76.53%), respectively. These findings showed that the use of M. pulegium and O. vulgare in combination with black soap or in double sprays could be incorporated in the management package for the control of the wild cochineal D. opuntiae, as a safe and natural alternative to chemical insecticides.

Biological Control of Onion White Rot Disease using Bacillus spp. Isolated from Egyptian Soil

The antagonistic ability of eleven bacterial isolates against Sclerotium cepivorum, causal agent of onion white rot disease (OWR), was determined in vitro and the best five isolates were identified as Bacillus pumilus (BP1 and BP2) and B. marinus (BM1, BM2 and BM3). The in vitro antagonistic efficacy ranged between 11.1 to 68.9% depending on the concentration of the bacterial cell suspension and number of applied sprays under greenhouse and field conditions. It was found that using double sprays with B. pumilus (BP2) in the greenhouse experiment gave the highest efficacy in reducing OWR (93.8%) at the concentrations of 10 and 20 ml/l. In case of field experiment there was no significant deference between number of sprays or the tested bacteria in reducing infection percentage of OWR. The significant difference was reported only between the concentrations of the bacterial suspension during the two growing seasons 2008/2009 – 2009/2010. In case of using one spray during season 2008/2009, the most effective bacteria in reducing OWR was B. pumilus (BP2) giving 64.7 and 61.6% efficacy when used at the concentrations 20ml/l and 10 ml/l, respectively, followedby B. marinus (BM3 ) which gave 58.2% at the concentration 20ml/l. On the other hand, when two sprays of bacterial suspension were used B. marinus (BM1) and B. pumilus (BP1) gave the highest efficacy in reducing OWR reached 63.7 and 63.4%, respectively. During season 2009/2010 B. pumilus (BP2) was the most effective bacteria reached 80.0% efficacy followed by B. marinus (BM3 ) recorded 76.9% when both used at the concentration 20ml/l for one spray. When two sprays were used, B. marinus (BM2) gave the highest percentage of efficacy in reducing OWR (87.3%). Data showed that applying the tested bacteria at any concentration, either once or twice, significantly increased onion bulb yield compared with control treatment during the two growing seasons.

Effectiveness of microbial and botanical insecticides in the control of Bemisia tabaci and Frankliniella occidentalis on ornamental plants1, 2

Results on the efficacy of a microbial insecticide (Paecilomyces fumosoroseus PFR‐97 WDG) and botanical insecticides (Neemix and SuperNeem 4.5) are presented. PFR‐97 WDG at three concentrations (0.1%, 0.2% and 0.4%), Neemix (0.4%) and SuperNeem 4.5 (0.04%) were applied as double sprays at 7‐day intervals against Bemisia tabaci on poinsettias. PFR‐97 WDG (0.4%) and SuperNeem 4.5 (0.04% and 0.08%) were also applied in a programme consisting of two spray treatments at 7‐day intervals against Frankliniella occidentalis on glasshouse roses.

Utility ofBacillus sphaericusin controllingCulex tritaeniorhynchusbreeding

Freeze-dried powder preparation of a streptomycin-resistant (Str) mutant of Bacillus sphaericus B.42 was applied against Culex tritaeniorhynchus larvae breeding in paper factory effluent. Whether applied as single, double or triple sprays on days 0, 1 and 2, respectively, a complete control of larvae was observed only until day 7 post application. Though the applied strain of B. sphaericus persisted (in the sprayed pits) at least until 91 days, as evident from larval resurgence, the sprayed B. sphaericus did not recycle in paper factory effluent. Whenever the heat-resistant spore counts dropped below approx. 600/ml, a build-up in larval population was observed. The Str mutant strain of B. sphaericus used in the present study seems to be an effective biocide capable of persisting and controlling C. tritaeniorhynchus larvae breeding in such a highly polluted water habitat as paper factory effluent.

Induction of bolting by gibberellic acid in rosettes of diffuse (Centaurea diffusa) and spotted (C. maculosa) knapweed

An attempt was made to induce synchronous bolting of knapweed (Centaurea spp.) rosettes with gibberellic acid (GA3) under greenhouse conditions. Single or double (2 weeks apart) sprays of GA3 (0, 0.3 × 10−4, and 1.5 × 10−4 M) were applied to 10- to 115-day-old diffuse knapweed (C. diffusa Lam.) rosettes. With the exception of 10- and 25-day-old rosettes, highly synchronous bolting was induced by double applications of 1.5 × 10−4 M GA3. Bolted plants flowered within 8 to 10 weeks of treatment but did not form seeds because of the absence of pollinators in the greenhouse. The size of bolted plants and the percentage of plants bearing flowers depended on rosette age at the time of GA3 application. With a single GA3 application or with two applications at lower concentration, uneven and (or) irregular bolting occurred. Occasionally, the initial rapid stem growth induced by GA3 was arrested, resulting in the formation of aerial rosettes. GA3 also induced bolting in spotted knapweed (C. maculosa Lam.). Induction of synchronous bolting may be useful in mechanical, biological, and (or) environmental (e.g., winter-killing) control of biennial weeds. Its feasibility under field conditions, however, remains to be demonstrated.

Effectiveness of soil dressings and foliar sprays of copper sulphate in correcting copper deficiency of wheat (Triticum aestivum) in Queensland

One field and two glasshouse trials were conducted to test the effectiveness of soil and foliar applications of copper sulphate in correcting copper deficiency of wheat on a severely deficient, nearneutral clay soil in the Western Downs region of Queensland. In the field, when wheat was stressed for water from late tillering (Feekes stage 5) to anthesis (Feekes stage 11) , soil dressings of 2.5-10.0 kg CuSO4.5H2O ha-1 increased early vegetative growth but foliar symptoms of copper deficiency reappeared during stem elongation, and grain yields were negligible at all rates. A single foliar spray of 2% CuSO4.5H2O applied at mid-tillering (Feekes stage 3) also did not correct the deficiency completely: foliar symptoms reappeared and grain yield was low (141 kg ha-1). A double spray treatment, the first applied at mid-tillering and the second just before booting (Feekes stage 10), was more effective and resulted in a grain yield of 800 kg ha-1. In a glasshouse experiment supplied with adequate water, a soil dressing equivalent to 16 kg CuSO4.5H2O ha-1 (3.2 mg Culpot) completely corrected the deficiency. In a second glasshouse experiment, 2% CuSO4.5H2O solution was applied as single sprays at Feekes stages 3, 8, 9, 10 or 11, or as double sprays at Feekes stages 3 + 8, 3 + 9, 3 + 10 or 3 + 11. The most effective single spray was that applied at Feekes stage 10, but maximum dry matter and grain yield were obtained when a double spray was applied at Feekes stage 3 + 10. The effectiveness of soil and foliar applications of CuSO4.5H2O for correcting Cu deficiency of dryland wheat in Queensland soils are discussed in relation to water regime and supplying adequate Cu for both vegetative and reproductive growth.

Red Color Enhancement of Pepper Fruits by Multiple Applications of Ethephon1

Abstract Ethephon [(2-chloroethyl) phosphonic acid] increased the yield of red fruit and reduced green fruit and total yields on 5 cultivars of peppers (Capsicum annuum L.) in the greenhouse. The effectiveness of ethephon was dependent on its concentration, the number of sprays, and cultivar. The cultivar Shepherd was the most sensitive to ethephon. A 10-ppm spray applied twice to ‘Shepherd’ was more effective in promoting red fruit coloring than any of the single sprays. Double or single sprays were equally effective in ‘Sweet Hungarian’, ‘Cascabella,’ and, to a lesser degree, ‘Staddon’s Select’, but double sprays were more effective in ‘Vinedale.’ The higher single concentrations of ethephon caused more chlorosis, defoliation, and fruit abscission than repeated application at lower concentration, and total yields were substantially reduced. In the field, 3 applications of 300 ppm ethephon significantly increased yield of red fruit and decreased green fruit in ‘Vinedale’, whereas all multiple applications were equally effective on ‘Shepherd.’ Only a single 750 ppm ethephon treatment significantly promoted fruit ripening in ‘Staddon’s Select.’ Ethephon effectively concentrated fruit maturity in the field for once-over harvest without reducing yield.

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.

Effect of Propanil on Weed Growth and Yield of IR 20 Rice Under Different Seeding Methods and Rates

Propanil spray once (3.5 kg ai./ha) or twice (7.0 kg ai /ha) were compared with hand weeding and no weeding for their herbicidal efficiency with 18-20 rica raised under different seeding methods and rates. Double sprays of propanil reduced, the weeds by 76 per cent and was close to two hand weedings. The weeding methods had significant influence on the number of productive tillers per unit area and the filled grains per panicle, Both for grain and straw yield two sprays of propanit ware as effective as two hand weedings. Transplanting contributed to greater tillering and higher grain yield while dibbling was on par with transplanting when adequate check of weeds was provided.

Growth and Flowering Response of Deciduous Azaleas to Growth Retardants1

Abstract The no. of flower buds on ‘Gibraltar’ Exbury azaleas (Rhododendron spp.) was increased by single sprays of succinic acid-2,2-dimethylhydrazide (SADH) at 7,500 to 20,000 ppm, 1-propyl phosphonic acid (PPA) at 1000 ppm, 5-chloro, 2-thenyl, tri-n-butyl-phosphoniumchloride (CTBP) at 1000 and 3000 ppm, and α-cyclopropyl -α-(methoxy-phenyl)-5-pyrimidinemethanol (ancymidol) at 250 and 500 ppm. Applications in July reduced plant ht. Early August applications of SADH had less effect on no. of flower buds than early July applications and did not reduce plant ht. Double sprays of (2-chloroethyl) trimethyl ammonium chloride (chlormequat) at 2000 and 4000 ppm did not affect ht or no. of flower buds. A soil drench of 2,4-dichlorobenzyl-tributylphosphonium chloride (CBBP) at 0.5 or 1.0 g per plant increased the no. of flower buds on ‘Cecile’ and ‘Renne’ Exbury azaleas.

Yield Reduction of Oats Caused by the Cereal Leaf Beetle1

Field research was conducted in Berrien County, Michigan, during the summer of 1967 on several aspects of oat productivity effected by feeding damage of a large population of Oulema melanopus (L.). Various degrees of population control were achieved with granular carbofuran applied as a broadcast soil-surface treatment before egg hatching started and single or double sprays of malathion applied at time of peak larval numbers. A 3 lb per acre rate of carbofuran maintained cereal leaf beetle-free plants. Untreated plots showed a grain yield reduction of 48.8%, or 4.7% per larva per stem for each of the 10.4 larvae per stem. Other maximum reductions were an additional 3.3% in 1/13 inch screening losses. 14.6% in plant height, 14.2% in kernel weight, 40.9% in kernel number, and 30.2% in straw weight. Early application of 1 or 3 lb of carbofuran per acre provided seasonlong control.