Air-tower sprayers increase spray application efficiency in mature citrus trees

Summary. Conventional pesticide spraying in citrus crops with low-profile sprayers results in pest management problems because of the poor distribution of pesticide throughout the tree. Pesticide losses, particularly drift, are a concern with this type of sprayer especially in orchards situated in or near urban areas. The spray deposit on citrus leaves and fruit and off-target losses (canopy run-off and drift) were determined for air-assisted low-profile sprayers and air-assisted sprayers fitted with tower air conveyors (air-towers). The air-tower sprayers produced even distribution of leaf spray deposits through the full height of the tree canopy while the low-profile sprayers produced decreasing leaf spray deposits with increasing height in the trees. The Metters tower sprayer and Cropliner low-profile sprayer resulted in increasing deposits from the 0˚ axis through to the 90˚ axis to sprayer travel while the Barlow tower sprayer and the Hardi low-profile sprayer produced a more even distribution of deposits through the axes to sprayer travel. Fruit deposits were not significantly different between sprayers. The Barlow tower sprayer produced significantly less canopy spray run-off compared with the low-profile sprayers. The Barlow tower sprayer resulted in a significant reduction in spray drift in the above tree zone compared with the Hardi low-profile sprayer. Better distribution of pesticides in citrus tree canopies will improve pest control especially in the top sections of the tree as this is where the greatest increase in pesticide deposit is achieved with air-tower sprayers. Both ground and air contamination from pesticides can also be reduced by using sprayers fitted with air-tower conveyors designed to produce even airflows for the full height of the citrus trees being sprayed.

Download Full-text

Spray Volume, Canopy Density, and Other Factors Involved in Thinner Efficacy

HortScience ◽

10.21273/hortsci.33.3.553d ◽

1998 ◽

Vol 33 (3) ◽

pp. 553d-553

Author(s):

C.R. Unrath

Keyword(s):

Tree Height ◽

Tree Canopy ◽

Tree Size ◽

Water Volume ◽

Canopy Density ◽

The North ◽

Run Off ◽

Tree Canopies ◽

Average Water ◽

Water Volumes

Historically, most airblast chemical applications to apple orchards used a single “average” water volume, resulting in variability of coverage with tree size and also the greatest variable in chemical thinning. This coverage variability can be eliminated by properly quantifying the tree canopy, as tree row volume (TRV), and relating that volume to airblast water rate for adequate coverge. Maximum typical tree height, cross-row limb spread, and between-row spacing are used to quantify the TRV. Further refinement is achieved by adjusting the water volume for tree canopy density. The North Carolina TRV model allows a density adjustment from 0.7 gal/1000 ft3 of TRV for young, very open tree canopies to 1.0 gal/1000 ft3 of TRV for large, thick tree canopies to deliver a full dilute application for maximum water application (to the point of run-off). Most dilute pesticide applications use 70% of full dilute to approach the point of drip (pesticide dilute) to not waste chemicals and reduce non-target environmental exposure. From the “chemical load” (i.e., lb/acre) calculated for the pesticide dilute application, the proper chemical load for lower (concentrate) water volumes can be accurately determined. Another significant source of variability is thinner application response is spray distribution to various areas of the tree. This variability is related to tree configuration, light, levels, fruit set, and natural thinning vs. the need for chemical thinning. Required water delivery patterns are a function of tree size, form, spacing, and density, as well as sprayer design (no. of nozzles and fan size). The TRV model, density adjustments, and nozzle patterns to effectively hit the target for uniform crop load will be addressed.

Download Full-text

Stem Flow, Throughfall, and Canopy Interception of Rainfall by Citrus Tree Canopies

HortScience ◽

10.21273/hortsci.32.6.1059 ◽

1997 ◽

Vol 32 (6) ◽

pp. 1059-1160 ◽

Cited By ~ 8

Author(s):

Y.C. Li ◽

A.K. Alva ◽

D.V. Calvert ◽

M. Zhang

Keyword(s):

Tree Canopy ◽

Storm Event ◽

Citrus Paradisi ◽

Citrus Tree ◽

Canopy Interception ◽

Canopy Effect ◽

Tree Canopies ◽

Stem Flow ◽

Citrus Cultivar ◽

Rain Events

It is generally believed that the interception of rain by the citrus tree canopy can substantially decrease the throughfall under the canopy as compared to that along the dripline or outside the canopy (incident rainfall). Therefore, the position of placement of soil-applied agrichemicals in relation to the tree canopy may be an important consideration to minimize their leaching during rain events. In this study, the distributions of rainfall under the tree canopies of three citrus cultivars, `Marsh' grapefruit (Citrus paradisi Macf.), `Hamlin' orange (Citrus sinensis L. Osbeck), and `Temple' orange (Citrus hybrid), were evaluated at four directions (north, south, east, west), two positions (dripline and under the canopy), and stem flow. There was not a significant canopy effect on rainfall amounts from stem flow or dripline, compared with outside canopy, for any citrus cultivar or storm event. However, throughfall varied significantly among the four cardinal directions under the canopy of all three citrus cultivars and was highly related to the wind direction. Among the three citrus cultivars evaluated in this study, throughfall, stem flow, and canopy interception accounted for 89.5% to 92.7%, 0.5% to 4.7%, and 5.8% to 9.3% of the incident rainfall, respectively.

Download Full-text

Impacts of the Tree Canopy and Chemical Reactions on the Dispersion of Reactive Pollutants in Street Canyons

Atmosphere ◽

10.3390/atmos12010034 ◽

2020 ◽

Vol 12 (1) ◽

pp. 34

Author(s):

Franchesca G. Gonzalez Olivardia ◽

Tomohito Matsuo ◽

Hikari Shimadera ◽

Akira Kondo

Keyword(s):

Chemical Reactions ◽

Urban Areas ◽

Numerical Experiments ◽

Tree Canopy ◽

Observation Data ◽

Street Canyons ◽

Urban Street ◽

Proposed Model ◽

Tree Canopies ◽

Computational Fluid Dynamics Cfd

Traffic-related air pollution in street canyons can cause health problems for pedestrians. In order to clarify the behavior of reactive pollutants, such as NOx and O3, in street canyons, a computational fluid dynamics (CFD) model coupled with a chemistry model and tree canopy model was developed, and then, a set of numerical experiments were performed to investigate the impacts of chemical reactions and aerodynamic effects of trees planted in a canyon. The results were compared with the observation data. Through the results of the numerical experiments designed to simulate a realistic urban street canyon, it was found that chemical reactions have a dominant impact on the NO/NO2 ratio and O3 concentration. While the tree canopy had little impact on the NO/NO2 ratio, it had a moderate impact on the flow field in the canyon and the amount of NOx and O3 in the canyon. In accordance with the aerodynamic effects of tree canopies, the local NOx concentration in the experiments increased and decreased by up to 51% and 11%, respectively. The current findings of this study demonstrate the utility of the proposed model for conducting air quality investigations in urban areas.

Download Full-text

The Assessment of Level of Flash Floods Threat of Urbanised Areas

Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis ◽

10.11118/actaun201765020519 ◽

2017 ◽

Vol 65 (2) ◽

pp. 519-526 ◽

Cited By ~ 1

Author(s):

Pavla Štěpánková ◽

Miroslav Dumbrovský ◽

Karel Drbal

Keyword(s):

Czech Republic ◽

Urban Areas ◽

Flood Hazard ◽

Flash Floods ◽

Flood Risk Assessment ◽

Entire Area ◽

The Czech Republic ◽

Eu Directive ◽

Run Off ◽

Technical Measures

Flash floods (or torrential rain flooding) is another type of flood hazard which has caused casualties and significant property damages. A methodology for identification of urban areas, which can potentially be burdened by that type of flood hazard, was proposed. This method, also called Method of Critical Points (CP), is a repeatable process able to identify areas, which are significant in terms of formation of surface run‑off and erosion. As addition to the preliminary flood risk assessment according to EU Directive 2007/60/ES on the Assessment and Management of Flood Risks, the presented methodology was applied for the entire area of the Czech Republic and the results are being used for the updating of non‑technical measures, e.g. urban planning. In the article, the principles of methodology of CP are described and results of the first application in the Czech Republic are presented, as well as possible interpretations of them.

Download Full-text

Assessment of Tolerance of Some Tree Species to Air Contamination Using Air Pollution Tolerance and Anticipated Performance Indices in Isfahan City, Iran

Journal of Advances in Environmental Health Research ◽

10.32598/jaehr.9.1.1195 ◽

2021 ◽

Vol 9 (1) ◽

pp. 31-44

Author(s):

Masoud Hatamimanesh ◽

◽

Samar Mortazavi ◽

Eisa Solgi ◽

Ahmad Mohtadi ◽

...

Keyword(s):

Air Pollution ◽

Tree Species ◽

Urban Areas ◽

Ailanthus Altissima ◽

Tolerance Index ◽

Air Contamination ◽

Pollution Tolerance ◽

Morus Nigra ◽

Platanus Orientalis ◽

Anticipated Performance Index

Background: In the present study, the tolerance of plantain tree species (Platanus orientalis, Morus nigra and Ailanthus altissima) to air pollution was evaluated using Air Pollution Tolerance Index (ATPI) and Anticipated Performance Index (API) index in Isfahan city (Iran). Methods: For this purpose, three dominant trees growing at six stations in Isfahan was selected and then sampling of the tree leaves was performed, after being transferred to the laboratory, the ATPI and API index were calculated. Results: The results of calculating the ATPI in the leaves of M. nigra, P. orientalis and A. altissima species showed that the highest values of ATPI index was obtained in M. nigra at 20.77 and then detected in P. orientalis and A. altissima with the values 14.90 and 14.33 respectively. According to API values Morus nigra had the best performance (Score = 6 so it classified as the Excellent) while P. orientalis and A. altissima had very good and intermediate performance, respectively. Conclusion: According to ATPI and API index most tolerant tree species was Morus nigra, so it would be the most suitable species for plantation programme in urban and pollutant areas followed by Platanus orientalis and Ailanthus altissima. As well as our results suggest that Platanus orientalis and Ailanthus altissima can be used as bio-indicators of air pollution due to their low ATPI scores (lower than 16). The present study suggests that the combination of both the ATPI and API indices for identifying and selection of plant species is very useful for plantation in urban areas.

Download Full-text

Spray Penetration into the Citrus Tree Canopy from Two Air-Carrier Sprayers

10.13031/2013.9306 ◽

2002 ◽

Author(s):

Muhammad Farooq ◽

Masoud Salyani

Keyword(s):

Tree Canopy ◽

Citrus Tree ◽

Spray Penetration ◽

Air Carrier

Download Full-text

Making Way for Trees? Changes in Land-Use, Habitats and Protected Areas in Great Britain under “Global Tree Restoration Potential”

Sustainability ◽

10.3390/su12145845 ◽

2020 ◽

Vol 12 (14) ◽

pp. 5845

Author(s):

Martin A. Wilkes ◽

James Bennett ◽

Sara Burbi ◽

Sue Charlesworth ◽

Katharina Dehnen-Schmutz ◽

...

Keyword(s):

Great Britain ◽

Protected Areas ◽

Urban Areas ◽

Canopy Cover ◽

Tree Canopy ◽

Tree Planting ◽

Substantial Contribution ◽

Trade Offs ◽

Tree Canopy Cover ◽

Restoration Potential

Numerous tree planting initiatives have been launched worldwide, based on the idea that carbon capture by trees can help to limit global warming. A recent study estimated the additional tree canopy cover that could be established given the growing conditions in every square kilometre of land on earth that is not already forested, urbanised, or used for crop production. It reported a total “tree restoration potential” of >900 million ha worldwide and identified hotspots where opportunities for tree planting initiatives may be the greatest. With the potential for an estimated 4.2 million ha of additional canopy cover, one such hotspot is Great Britain. We quantify the extent of habitats, land uses, and protected areas that would be impacted by tree planting on this scale in Great Britain and discuss the potential social–ecological trade-offs involved. Our findings show that realising the “tree restoration potential” would mean a considerable upheaval for the British landscape with 30–50% of ecologically valuable habitats lost and a reduction of 44% in the area of improved grassland. Up to 21% of land protected by law for its ecological, scientific, scenic, or cultural value would be impacted. Importantly, we demonstrate that an alternative approach based on increasing tree canopy cover by up to 20% in urban areas and on cropland could make a substantial contribution to tree planting targets, potentially offsetting losses elsewhere. Such shifts in the structure and function of the British landscape will depend on deep changes in the food system, evidence-based decisions about which existing habitats to protect, and a long-term commitment to tree planting and maintenance.

Download Full-text

Effect of Various Irrigation Rates on Growth and Root Development of Young Citrus Trees in High-Density Planting

Plants ◽

10.3390/plants9111462 ◽

2020 ◽

Vol 9 (11) ◽

pp. 1462

Author(s):

Said A. Hamido ◽

Kelly T. Morgan

Keyword(s):

Leaf Area ◽

Tree Growth ◽

Root Development ◽

Root Length ◽

Planting Density ◽

Citrus Tree ◽

Irrigation Rate ◽

Root Lifespan ◽

Canopy Volume ◽

Citrus Trees

Citrus yields have declined by almost 56% since Huanglongbing (HLB) was first found in Florida (2005). That reduction forced citrus growers to replant trees at much higher densities to counter-balance tree loss. The current project aims to determine how much water is required to grow citrus trees at higher planting densities without reducing their productivity. The study was initiated in November 2017 on eight-month-old sweet orange (Citrus sinensis) trees grafted on the ‘US-897′ (Cleopatra mandarin × Flying Dragon trifoliate orange) citrus rootstock planted in the University of Florida, Southwest Florida Research and Education Center (SWFREC) demonstration grove, in Immokalee, FL (lat. 26.42° N, long. 81.42° W). The soil in the grove is Immokalee fine sand (Sandy, siliceous, hyperthermic Arenic Alaquods). The demonstration grove included three densities on two rows of beds (447, 598, and 745 trees per ha) replicated four times each and three densities of three rows of beds (512, 717, 897 trees per ha) replicated six times. Each density treatment was irrigated at one of two irrigation rates (62% or 100%) during the first 15 months (2017–2019) then adjusted (2019–2020) to represent 26.5, 40.5, 53, and 81% based on recommended young citrus trees evapotranspiration (ETc). Tree growth measurements including trunk diameter, height, canopy volume, leaf area, and root development were evaluated. During the first year, reducing the irrigation rate from 100% to 62% ETc did not significantly reduce the young citrus tree growth. Conversely, the lower irrigation rate (62% ETc) had increased citrus tree’s leaf area, canopy volume and tree heights, root lifespan, and root length by 4, 9, 1, 2, and 24% compared with the higher irrigation rate (100%), respectively. Furthermore, the root lifespan was promoted by increasing planting density. For instance, the average root lifespan increased by 12% when planting density increased from 447 to 897 trees per ha, indicating that planting young trees much closer to each other enhanced the root’s longevity. However, when treatments were adjusted from April 2019 through June 2020, results changed. Increasing the irrigation rate from 26.5% to 81% ETc significantly enhanced the young citrus tree growth by increasing citrus tree’s canopy volume (four fold), tree heights (29%), root lifespan (86%), and root length (two fold), respectively. Thus, the application of 81% ETc irrigation rate in commercial citrus groves is more efficient for trees from two to four years of age.

Download Full-text