Dormant Sprays Research Articles

Optimizing Fungicide Sprays to Tackle Powdery Mildew (Uncinula necator) At The Right Time For healthy grapes production

Introduction: Powdery mildew, caused by the fungus Uncinula necator, is a prevalent and harmful disease affecting grapevines, resulting in decreased fruit set and yield. This study aimed to evaluate the effectiveness of various fungicides and spray timings in managing U. necator in grape vineyards. Methods: A field trial was conducted in Pishin, Balochistan in 2020, employing a randomized complete block design with two factors: four fungicides (control, protective fungicide-Bordeaux mixture, curative fungicide-Elite 45 wp, systemic fungicide-Quintec) and four spray timings (dormant spray, bud break, one week before bloom, and berry formation). Results: The findings revealed significant variations in disease severity (PDI) among leaves, inflorescence, and bunches across different fungicides, spray timings, and their interactions. Application of the protective fungicide one week before bloom proved highly effective in preventing U. necator infection, resulting in the lowest PDI values for leaves (0.44%), inflorescence (0.67%), and bunches (0.0%). Curative fungicides sprayed at bloom stage also reduced PDI for inflorescence (2.17%) and bunches (3.56%). Systemic fungicides applied during berry formation exhibited lower PDI for inflorescence (6.44%) and bunches (4.0%) compared to other fungicides. The highest grape production (27.10 t ha-1) was achieved with the protective fungicide sprayed at bloom stage, followed by the curative fungicide at bloom stage (25.87 t ha-1). The negative and highly significant relationship (R2=0.809) between PDI of leaves and grape yield indicated that higher disease severity led to decreased yield. Conclusion: In conclusion, a protective fungicide spray before bloom, followed by a systemic fungicide spray at berry formation, effectively controls U. necator and ensures healthier and higher grape yields.

Management of San Jose Scale (Quadraspidiotus perniciosus) by HMOs and Insecticides in Apple Orchards of Kashmir, India

Apple is attached by number of insect pests, among them San Jose Scale (Quadraspidiotus perniciosus) is key pests. San Jose scale (SJS) attacks temperate fruit crop in the state of J&K. It sucks sap from, twigs, branches, and fruits, weakens the plant and the fruits having scale infestation is rendered unthrifty and unmarketable. The pest causes great loses to apple in quantity and quality and debilities apple tree by vigour and health. The objective of this study was to examine efficacy of HMOs as dormant sprays at different concentrations to manage San Jose scale (Quadraspidiotus perniciosus Comstock) and two insecticides viz Chlorpyriphose 25EC and Dimethoate 30Ec at different concentrations were checked for their bio-efficacy in same orchard in late spring during 2021-22. On the basis of pooled data for years for revealed that highest cumulative mean mortality (79.48%) was recorded with the application of Bal spray at concentration of 2.5% followed by 77.56%. mortality of SJS @ 2.5% concentration by HP oil. Chlorpyriphose recorded 71.98% pooled mean mortality at 0.03 5 concentration.

Non-target effects of agrichemicals applied in the fall or during the dormant season on subsequent development of Exobasidium leaf and fruit spot of blueberry

The basidiomycete Exobasidium maculosum causes Exobasidium leaf and fruit spot, an early-season disease of blueberry in the southern United States. Previous research suggested that the pathogen oversummers and overwinters epiphytically on the surface of blueberry bark and buds, most likely in its yeast stage. This is supported by the finding that a single dormant application of lime sulfur provides substantial control of the disease the following spring. As a surface resident for much of the year, E. maculosum is thus exposed to various horticultural and pest management practices which may affect its epiphytic population dynamics and impact subsequent disease development. The magnitude and consistency of such non-target effects was evaluated in multi-year field trials on susceptible ‘Premier’ and ‘Tifblue’ rabbiteye blueberry in southern Georgia. One fall application of stylet oil (timed to mimic sprays for blueberry bud mite control) or two fall applications of captan (timed to coincide with the management window for fungal foliar diseases) did not suppress Exobasidium leaf and fruit spot the following spring, whereas two fall applications of lime sulfur reduced the disease significantly (by 74.3% on average), albeit not to the same level as the late dormant lime sulfur standard (close to 90% average reduction across leaf and fruit spot intensity). A single late dormant spray of the growth regulator hydrogen cyanamide (a caustic compound with antimicrobial activity) suppressed disease intensity in most trials, but disease reduction was only partial (averaging 56.2% for leaf lesion density and 39.3% for fruit spot incidence). In contrast, a late dormant application of dormant oil consistently increased both leaf lesion density (by 80.7% on average) and fruit disease incidence (by 78.6%). The pronounced non-target effects associated with these off-season applications could explain variations in Exobasidium leaf and fruit spot risk among blueberry sites and years.

Management of san jose scale, Quadraspidiotus perniciosus Comstock in apple orchards of Kashmir through horticultural mineral oils

The field experiment, conducted with the objective of examining the efficacy of different concentrations of two oil dormant sprays of Arbofine extra along with standard check (ATSO) to manage san jose scale (Quadraspidiotus Perniciosus Comstock) in delayed dormant season of 2015-16, revealed highest comulative mean mortality of SJS (82.69%) with the application of 2.5 per cent of Arbofine extra followed by 80.71 per cent mortality of SJS with 2.0 per cent of Code-204 as against the standard check (ATSO) applied at 2.5 per cent concentration (80.12%) and the lowest (76.47 per cent) at 1.5 per cent concentration. Two parasitoids, Encarsia pernicious and Aphytis proclia and one predator Chilocorus infernalis were found on SJS twigs from the treated area. Arbofine extra @ 2.5 per cent concentration recorded mean yield (10.0 boxes) of ‘A’ grade followed by 8.33 boxes @ 2.0 per cent concentration.

Field Efficacy of Pesticides Against Dust Mites Oligonychus afrasiaticus (McGregor) (Acari: Tetranchidae) on Date Palm, Hillawi Cultivar

This study was carried out to evaluate some pesticides with two methods of control (preventative and curative) in a private field in the region of Abu Al-Khaseeb in Basrah province during the growing season of 2018 / 2019; treatments were applied in three dates (eight weeks, ten weeks and twelve weeks) after the pollination of the date palm trees (28/2/2019). The results recorded that the 1st spray was the most effective in reducing the population density of the dust mites compared to the second and third spraying rate (49.25, 45.40 and 42.69)% respectively. The dormant spray carried out in December 2018 that reduced the population density of the pest below the economic threshold by using Sulphur (200, 300 and 400) G/palm and Matrixine (1, 1.5 and 2) Ml.L-1; the population density was decreased to 7.88, 4.15 and 4.05 mites and to 7.53, 4.31 and 3.96 mites by controlling with Sulphur and Matrixine, respectively, compared to the untreated palms (8.63, 24.53 and 42.40 mites) at the sampling events 15 March, 15 April and 15 May.

Sodium arsenite effect on Vitis vinifera L. Physiology

Sodium arsenite (NaAsO2) was especially used as a dormant spray to control grapevine trunk diseases (GTDs) in European vineyards until 2003 when it was banned. It was an efficient product but it was banned due to high risk for human health and the environment. Now, as one of the consequences with climatic changes, GTDs threaten the sustainability of vineyards since no similar and efficacious sprays are presently available to reduce the impact of GTDs. Research efforts were devoted to identify other active ingredients and biological control agents but they remained limited in term of efficacy. New solutions might follow from a better understanding of the modes of action of sodium arsenite which are currently lacking, specially its impact on grapevine physiology. For this study, grafted plants cv. Tempranillo were sprayed by sodium arsenite at the end of the winter. During the vegetative period, the impact on plant physiology was studied by measurement of the photosynthetic activity, the vine growth and development, and some defense responses. Our results showed that arsenic was translocated throughout the vine with an increasing gradient from the leaves to the root system, that photosynthesis was firstly reduced and then stimulated, and that plant tolerance responses were induced especially antioxidant system. The activation of grapevine defense responses by sodium arsenite could be a complementary action to fight fungal pathogens in addition to the fungicide effect.

Assessing the Effectiveness of Dormant Sprays of Lime Sulfur to Control Eriophyes sp.2 in Pear Orchards

Assessing the Effectiveness of Dormant Sprays of Lime Sulfur to Control <i>Eriophyes</i> sp.2 in Pear Orchards

A review of diazinon use, contamination in surface waters, and regulatory actions in California across water years 1992-2014.

Diazinon is an organophosphorus insecticide that has been widely used in the USA and in California resulting in contamination of surface waters. Several federal and state regulations have been implemented with the aim of reducing its impact to human health and the environment, e.g., the cancellation of residential use products by the USEPA and dormant spray regulations by the California Department of Pesticide Regulation. This study reviewed the change in diazinon use and surface water contamination in accordance with the regulatory actions implemented in California over water years 1992-2014. We observed that use amounts began declining when agencies announced the intention to regulate certain use patterns and continued to decline after the implementation of those programs and regulations. The reduction in use amounts led to a downward trend in concentration data and exceedance frequencies in surface waters. Moreover, we concluded that diazinon concentrations in California's surface waters in recent years (i.e., water years 2012-2014) posed a de minimis risk to aquatic organisms.

Organophosphate Insecticide Activity Reduced when Mixed with Copper(II) Hydroxide in Peach Dormant Sprays

Abstract Dormant-season applications of copper-containing fungicides and organophosphate insecticides are common in Prunus spp. orchards, and these compounds are often mixed into a single application. However, copper(II) catalyzes the hydrolytic breakdown of many organophosphate insecticides. We measured the impact of tank-mixing these products using field efficacy data collected from 2002 to 2004 coupled with active ingredient degradation studies in the laboratory. Formulations of the organophosphate insecticides chlorpyrifos and diazinon were applied with and without the fungicide Cu(OH)2 in peach orchards, and the resulting peach twig borer (Anarsia lineatella Zeller) damage was measured. Laboratory experiments to quantify the degradation of the active organophosphate ingredient in various dry deposits from treatment solutions showed that addition of Cu(OH)2 to laboratory organophosphate solutions resulted in more rapid degradation of the active organophosphate ingredient in dry deposits stored at 100...

Disease and pest management in apple: Farmers' perception and adoption in J&amp;K state

Diseases and pests are one of the limiting factors for low productivity of the fruit crops in Kashmir valley, India. A study on management of resources with respect to disease and pest management of apple and extent of adoption of recommended plant protection technology was undertaken for increasing apple production in Kashmir valley of J and K State. District Baramulla was selected purposively on the basis of maximum area and production under apple crop. A sample size of 200 apple growers 50 each from 4 villages were selected randomly. The study revealed that the perception index regarding attributes of technology recommended in two diseases viz. San Jose Scale and Apple Scab was 68.88% and 80.76% in respect of profitability (83.97%), simplicity-complexity each 63.57% and 54.27 % for practicability attributes of technology. The data further showed that the farmers adoption level under Chemical control was high at silver tip to green tip stage (80%) and fruit let pea size stage (78%) and medium adoption was observed at pink bloom (bud) stage (74%), petal fall stage (74%) walnut size apple stage (70%) on Apple Scab similarly, the extent of adoption was low (45%) for mechanical and no chemical control measures under clean cultivation. In case of San Jose Scale the farmers adoption level regarding name of chemical, its dose, quantity of water required per acre for preparing spray solution and time of spray at late dormant spray, (feb, March) was high (80%). The findings will help to improve the level of farmers’ knowledge to increase apple production in Kashmir valley.

Incidence and management of coconut scale, Aspidiotus destructor signoret (Hemiptera: Diaspididae), and its parasitoids on mango (Mangifera sp.)

Populations of coconut scale, Aspidiotus destructor Signoret (Hemiptera: Diaspididae), and its parasitoids were surveyed on 4 mango cultivars in the southern district of Khyber Pakhtunkhwa, Pakistan, from July 2011 to June 2013. The populations of A. destructor built up in July and continued for 6 consecutive months reaching a peak in November 2011 (54 scales/leaf) and in October 2012 (44 scales/leaf). Two parasitoids, Aphytis melinus DeBach (Hymenoptera: Aphelinidae) and an Anagyrus sp. (Hymenoptera: Encyrtidae) were first observed in August, reaching peaks in November 2011–12 and 2012–13 (13.6 and 16.3% parasitism) and December 2011–12 and 2012–13 (14.2 and 14.9% parasitism), respectively for the two species. The efficacy of two winter oils, one IGR (pyriproxyfen 10.8 EC), one organophosphate (profenofos 500 EC), one pyrethroid (bifenthrin 10 EC), and two neonicotinoid insecticides (imidacloprid 20% SL and thiamethoxam 25 WP) were evaluated at recommended rates against 1st and 2nd instars and mature A. destructor on nursery plants and mature mango trees. In both cases, the highest A. destructor mortalities were recorded with petroleum oil, imidacloprid and pyriproxyfen. Thiamethoxam was effective after 14 days (70–80 % scale insect mortality) while bifenthrin showed good results against all life stage in the first 14 days. For management of A. destructor, parasitoids may be conserved by using oils and insect growth regulators (IGRs) while systemic insecticides may also be used in the case of severe infestations. The 1st spray must be applied in early August (before parasitoids emergence), the 2nd spray in October, as one spray controls the pest for one month. One dormant spray may be applied in February after pruning of infested leaves and branches to clean the plants from A. destructor for the next season.

Effect of Lime Sulfur on Changes of Fungal Diversity in Pear Fallen Leaves

This study was conducted to examine changes in the fungal community on fallen leaves of pear by treatment with lime sulfur. Although the lime sulfur could reduce the primary inoculum of several pathogens on spring season, the effect of lime sulfur has not been well determined scientifically. Fallen leaves infected by pear diseases in pear orchards in Naju were collected and treated with lime sulfur or water as a control. To determine the fungal diversity from each treatment, rDNA internal transcribed spacer (ITS) regions were analyzed after extraction of fungal genomic DNA from lime sulfur-treated or water-treated fallen leaves, respectively. The most common fungal species were Ascomycota and Basidiomycota in both treated leaves. However, the population dynamics of several fungal species including Alternari sp., Cladosporium sp., and Phomopsis sp., which are known as pear pathogens for skin sooty dapple disease, were quite different from each treated leaves. These results indicated that lime sulfur treatment led to changes of fungal communities on pear fallen leaves and could be applicable as a dormant spray.

Synthesis results from eight years of field testing insecticides against Asian citrus psyllid Diaphorina citri vector of huanglongbing: Considerations and Implications

Diaphorina citri also known as Asian citrus psyllid (ACP) vectors Candidatus Liberibacter asiaticus, causal organism of the Asian “huanglongbing” or citrus greening disease and therefore needs to be managed effectively. Forty-three insecticides containing 39 active ingredients (a.i) recommended or experimental were tested during the growing season in foliar sprays (171 treatments, 35 a.i) targeted at flushing trees and soil applications (26 treatments, 6 a.i) to control ACP in citrus between 2005-2012. Psyllid suppression varied with product and lasted 1-7 weeks using foliar sprays on mature trees and 6-33 weeks using soil drenches in young trees. Experimental insecticides tolfenpyrad (Apta 15 SC), flupyradifurone (Sivanto 200 SL), sulfoxaflor (Closer 240 SC), cyantraniliprole (Verimark), and Chromobacterium substugae (Grandevo/MBI-203 EP) performed equal to or better than recommended products. Unfortunately, eggs and young nymphs are protected inside unfolded leaves such that insecticidal sprays may kill more predators and parasitoids common during growing season that would otherwise attack immature ACP and other citrus pests. Addition of new insecticides will broaden the range of products available to control ACP. Nevertheless, one to two sprays of broad-spectrum insecticides during dormant winter period when most mature trees are not producing new growth and beneficial insects are scarce can provide up to 6 months of ACP suppression into growing season and also conserve beneficial insects. Therefore, psyllid suppression using one or two dormant winter sprays of broad-spectrum insecticides followed by regular monitoring and rotation of relatively selective chemistries during growing season will help to reduce incidence of huanglongbing, pest resistance to insecticides and secondary pest outbreaks.

Phytoseiidae on Blackberry in Central California

Winter collections (November through January 2006–2007) of phytoseiid mites were made from dormant buds in 19 different sites of wild blackberry and 13 different farms with commercial blackberry. Twelve different species were collected from wild blackberry, with Metaseiulus arboreus (Chant) being the dominant species, collected in all plots except one, in which no phytoseiids were found. Eight of these species are considered Type III generalist feeders. In commercial blackberry, phytoseiids were not only less numerous, but M arboreus, collected in all plots except one in which no phytoseiids were found, was the only species except for a single specimen of Galendromus occidentalis (Nesbitt). The low diversity of phytoseiids on commercial blackberry may be related to the lack of diversity in plants, alternate foods and the adverse effects of dormant sprays.

Spatial and temporal variation in nutrient parameters in stream water in a rural-urban catchment, Shikoku, Japan: Effects of land cover and human impact

Seasonal and spatial variations in major ion chemistry and isotope composition in the rural-urban catchment of the Shigenobu River were monitored to determine the influences of agricultural and urban sewage systems on water quality. Temporal patterns of biochemical oxygen demand (BOD), total nitrogen (TN), total phosphorus (TP), and suspended sediment (SS) were examined at four sites in the rural-urban catchment. Urban land cover, incorporating the effects of increased population, domestic water use, and industrial wastewater, was positively associated with increases in water pollution and was included as an important explanatory variable for the variations in all water quality parameters. Significant trends were found in each parameter. BOD concentrations ranged widely, and were high in urban regions, due to the presence of a waste water treatment plant. TN and SS showed various trends, but did not vary widely, unlike TP. TP concentrations varied greatly, with high concentrations in cultivated areas, due to fertilizer use. Local water quality management or geology could further explain some of the variations in water quality. Non-point-source pollution exhibited strong positive spatial autocorrelation, indicating that incorporating spatial dimensions into water quality assessment enhances our understanding of spatial patterns of water quality. Data from the Ministry of Land Infrastructure and Transport (MLIT) and Environment Ministry (EM) were used to investigate trends in land management. Stepwise regression analysis was used to test the correlation between specific management practises and substance concentrations in surface water and sediment. MLIT and EM data for 1981–2003 showed an increase in TN, TP, and SS concentrations in surface water. High levels of fertilizer in dormant sprays and domestic water use were associated with high pesticide concentrations in water and sediment. This paper presents a novel method of studying the environmental impact of various agricultural management practises and recommends a management strategy that combines the use of reduced-risk pesticides with irrigation and non-irrigation periods in paddy fields.

Application of pesticide transport model for simulating diazinon runoff in California’s central valley

Dormant spray application of pesticides to almond and other stone fruit orchards is the main source of diazinon during the winter in California’s central valley. Understanding the pesticide transport and the tradeoffs associated with the various management practices is greatly facilitated by the use of physically-based contaminant transport models. In this study, performance of Joyce’s et al. (2008) pesticide transport model was evaluated using experimental data collected from two ground treatments such as resident vegetation and bare soil. The model simulation results obtained in calibration and validation process were analyzed for pesticide concentration and total load. The pesticide transport model accurately predicted the pesticide concentrations and total load in the runoff from bare field and was capable of simulating chemical responses to rainfall-runoff events. In case of resident vegetation, the model results exhibited a larger range of variation than was observed in the bare soil simulations due to increased model parameterization with the addition of foliage and thatch compartments. Furthermore, the model was applied to study the effect of runoff lag time, extent of crop cover, organic content of soil and post-application irrigation on the pesticide peak concentration and total load. Based on the model results, recommendations were suggested to growers prior to implementing certain management decisions to mitigate diazinon transport in the orchard’s spray runoff.

Understanding the Occurrence and Transport of Current-Use Pesticides in the San Francisco Estuary Watershed

The occurrence and potential effects of current-use pesticides are of concern in the San Francisco Estuary watershed but our understanding of the spatial and temporal distribution of contamination is limited. This paper summarizes almost two decades of historical data and uses it to describe our current knowledge of the processes controlling the occurrence of current-use pesticides in the watershed. Monitoring studies analyze fewer than half of the pesticides applied in the watershed and most of our knowledge is about inputs of dissolved pesticides in the upper watershed. The four major seasonal patterns of riverine inputs of pesticides to the estuary can be identified by usage and transport mechanism. Dormant spray insecticides applied to orchards and herbicides applied to a variety of crops are transported by rainfall during the winter. Alfalfa pesticides are detected following rainfall and irrigation return flow in the spring, and rice pesticides are detected following release of rice field water in the summer. Irrigation return flows transport a variety of herbicides during the summer. In addition, pesticides applied on Delta islands can cause elevated pesticide concentrations in localized areas. Although not as well characterized, urban creeks appear to have their own patterns of insecticide concentrations causing toxicity throughout most of the year. Current-use pesticides have also been detected on suspended and bed sediments throughout the watershed but limited data make it difficult to determine occurrence patterns. Data gaps include the lack of analysis of many pesticides (or degradates), changing pesticide use, limited information on pesticide transport within the Delta, and an incomplete understanding of the transport and persistence of sediment-associated pesticides. Future monitoring programs should be designed to address these data gaps.

Evaluation of water quality in an agricultural watershed as affected by almond pest management practices

In the last decade, the detection of organophosphate (OP) pesticides in the San Joaquin River watershed has raised concerns about water quality. This study examined the influences of almond pest management practices (PMPs) on water quality. The Soil and Water Assessment Tool (SWAT) model was employed to simulate pesticide concentration in water as affected by different PMPs. California Pesticide Use Reporting (PUR) data were used to investigate PMP use trends. Stepwise regression analysis was performed to test the correlation between specific PMP use and pesticide concentrations in surface water and sediment. Our results showed an increasing use of reduced risk pesticides and pyrethroids on almonds. SWAT simulation over the period of 1992–2005 showed decreases in OP concentrations in surface water. High OP and pyrethroid use in dormant sprays was associated with high pesticide concentrations in water and sediment. Almond pesticide use was proved to have significant impacts on the pesticide load in the San Joaquin River watershed. The PMP which combines the use of reduced risk pesticides with no dormant spray was recommended for almond orchard use. This paper presented a novel method of studying the environmental impacts of different agricultural PMPs. By combining pesticide use surveys with watershed modeling, we provided a quantitative foundation for the selection of PMPs to reduce pesticide pollution in surface water.

Effect of bark-scraping, dormant spray of petroleum oil and applying pesticide in late spring on density of Japanese mealybug, Planococcus kraunhiae (Kuwana), in persimmon

There are three generations of Japanese mealybug, Planococcus kraunhiae (Kuwana), on persimmon each year. Chemical control of this bug is usually conducted in June and August when 1st instar nymphs appear which is the most susceptible to insecticides. However, the following additional countermeasures should be taken in heavily infested orchards: 1) eliminating overwintering nymphs by scraping away the tree bark, 2) spraying the tree with petroleum oil in winter and 3) applying pesticides from late April to early May when overwintering nymphs move to the top of shoots.

Toxicity of storm‐water runoff after dormant spray application in a French prune orchard, Glenn County, California, USA: Temporal patterns and the effect of ground covers

Organophosphorous (OP) insecticides, especially diazinon, have been detected routinely in surface waters of the Sacramento and San Joaquin River watersheds, coincident with rainfall events following their application to dormant orchards during the winter months. Preventive best management practices (BMP) aim at reducing off-site movement of pesticides into surface waters. Two proposed BMPs are: The use of more hydrophobic pyrethroid insecticides believed to adsorb strongly to organic matter and soil and the use of various types of ground cover vegetation to increase the soil's capacity for water infiltration. To measure the effectiveness of these BMPs, storm water runoff was collected in a California prune orchard (Glenn County, CA, USA) during several rainstorms in the winter of 2001, after the organophosphate diazinon and the pyrethroid esfenvalerate were applied to different orchard sections. We tested and compared acute toxicity of orchard runoff from diazinon- and esfenvalerate-sprayed sections to two species of fish (Pimephales promelas, Onchorhynchus mykiss) and three aquatic invertebrates (Ceriodaphnia dubia, Simocephalus vetelus, Chironomus riparius), and determined the mitigating effect of three ground cover crops on toxicity and insecticide loading in diazinon-sprayed orchard rows. Runoff from the esfenvalerate-sprayed orchard section was less toxic to waterflea than runoff from the diazinon-sprayed section. However, runoff from the orchard section sprayed with esfenvalerate was highly toxic to fish larvae. Samples collected from both sections one month later were not toxic to fish, but remained highly toxic to invertebrates. The ground cover crops reduced total pesticide loading in runoff by approximately 50%. No differences were found between the types of vegetation used as ground covers.