Optimization of the spraying equipment and technology used in ornamental crops

In 2006, a research project concerning the optimization of the spraying equipment and technology used in ornamental crops was started. First, several greenhouse growers were surveyed on the spray equipment and technology they were using for their plant protection. Later on, different parts of their equipment were evaluated. It this way, we could advice the connected growers on how to improve their own techniques and equipment. Additionally, the survey showed that growers predominantly use knapsack sprayers and lances for crop protection purposes. These techniques are often proven to be less effective compared to spray booms, which could explain the high application rates (up to 6650 L ha(-1)) used by most growers. Since spray boom equipment could enhance spray distribution and minimize labour cost, operator exposure; the usability of this technique in ornamental crops was studied by means of laboratory tests, field trials and bio-efficacy experiments.     

Reducing insecticide volume and nontarget effects of ambrosia beetle management in nurseries

Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are increasingly important pests of nursery-grown trees because of the arrival of several invasive species. Ambrosia beetles bore into young trees and inoculate them with ambrosia fungus, which interferes with vascular transport resulting in limb or tree death. In spring, when beetles are active, growers make frequent applications of pyrethroid insecticides to susceptible tree species to deter beetles from boring into trees. Applications often are made with airblast sprayers that forcefully release insecticide mist that billows through nursery beds. Our objective was to compare the environmental, nontarget, and economic effects of airblast sprayer applications to applications made with a new dual-nozzle spray wand that makes targeted applications only to tree trunks where beetles attack. Through replicated experiments at commercial nurseries, we found that 5 times more insecticide was released by airblast sprayers than the manual spray wand. The extra insecticide from airblast applications landed on tree canopies, between rows, and left the nursery beds as drift. As a consequence of not spraying tree canopies, 50% more natural enemies and 50% fewer spider mites were captured in nursery beds treated with the manual spray wand than beds treated with the airblast sprayer. Manual applications require 12 times more labor than airblast applications. However, increased need for expensive miticide applications may make manual applications an economically feasible strategy for integrated pest management (IPM) of ambrosia beetles in nurseries.     

Comparison of the performance between a spray gun and a spray boom in ornamentals

Flemish greenhouse growers predominantly use handheld spray guns and spray lances for their crop protection purposes although these techniques are known for their heavy workload and their high operator exposure risks. Moreover, when these techniques are compared with spray boom equipment, they are often found to be less effective. On the other hand, handheld spraying techniques are less expensive and more flexible to use. Additionally, many Flemish growers are convinced that a high spray volume and spray pressure is needed to assure a good plant protection. The aim of this work was to evaluate and compare the spray deposition, penetration and uniformity between a manually pulled horizontal spray boom and a spray gun under controlled laboratory conditions. In total, six different spray application techniques were evaluated. In general, the total deposition results were comparable between the spray boom and the spray gun applications but the boom applications resulted in a more uniform spray distribution over the crop. On a plant level, the spray distribution was not uniform for the different techniques with highest deposits on the upper side of the top leaves. Using spray guns at a higher spray pressure did not improve spray penetration and deposition on the bottom side of the leaves. From the different nozzle types, the XR 80 03 gave the best results. Plant density clearly affected crop penetration and deposition on the bottom side of the leaves.     

A generic method of pesticide dose expression: Application to broadcast spraying of apple trees

The recommended dose for many pesticides is expressed as a constant mass or volume per unit ground area covered by the crop. This method of dose expression is well suited to boom spraying where a reasonably uniform horizontal distribution of deposit can be achieved with a well‐adjusted sprayer. However, in many practical situations (e.g. broadcast spraying of apple trees or other row structures where the spray application is made from within the canopy) the horizontal deposit distribution is strongly influenced by the crop area density and other crop structural parameters. This paper describes a generic method of pesticide dose expression to investigate these effects. The method incorporates a model of the spray volume deposition process. The model assumes that the pesticide deposit is proportional to the tank‐mix concentration of pesticide. The model also assumes that spray volume deposit is proportional to the applied spray volume per unit row length and is inversely proportional to a crop length scaling function L (i.e. a parameter with the units of length that is expressed as a generic function of different crop parameters). The useful working range of this model is bounded by the condition for high spray volume where target losses become significant due to saturation and the condition for very low volume where evaporative transport losses become significant. Within this framework, four different models are formulated using first‐order approximations for the length‐scale as functions of the following crop parameters: tree row spacing, tree row height, tree area density and tree row volume to ground area ratio. Published measurements of crop structure and spray volume deposit on apple trees are compared with the output from these models. Light detection and range (LIDAR) measurements of apple orchards are presented and used in conjunction with the different models to predict pesticide use associated with different methods of dose expression. The results demonstrate the relative potential for varying the pesticide application rate according to the different crop parameters. The results enable the identification of reference orchards that could be used to establish worst‐case pesticide application rates for registration purposes. The results also enable the identification of other orchards and growth stages where pesticide application rate might be reduced by up to a factor of five and give the same pesticide deposit as the reference structure.     

A comparison of fungicide spray volumes for the control of coffee berry disease

A continuation of previous trials in which three sprayers were used to apply 8.4 g. of Perenox in a range of spray volumes from 0.2 to 1.7 l. per tree confirmed that the volume of spray did not affect greatly the deposit retained on the branch surface. Branches were able to retain up to about 250 mg. Cu/m.² and it is considered that a volume equivalent to 100 gal./acre would provide the greatest margin of safety to compensate for inaccuracies of application, while avoiding serious run-off. Where coffee was well pruned, intensive copper spraying raised the annual yield by about 2 cwt. of clean coffee per acre. Copper spraying did not provide an adequate control of coffee berry disease and, under certain circumstances, increased incidence.     

Volumes of petroleum spray oil required for control of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) in mature citrus orchards

Studies on the relationship between volume of spray and suppression of citrus leafminer ( Phyllocnistis citrella ) oviposition by petroleum spray oil on 4 m-high mature orange trees showed a negative exponential relationship between spray volume and the number of mines per leaf. Significant reductions in the number of mines per leaf compared to unsprayed trees was achieved at spray volumes of ≥ 3300 L/ha using oscillating boom and at ≥ 3200 L/ha using rotary atomiser sprayers. However, improvements in efficacy at volumes over 3200–3300 L/ha were not significant and so of little practical value. The optimal spray volumes for citrus leafminer control are therefore suggested to be 3000–3500 L/ha. No significant difference in effectiveness was found between the oscillating boom at 3300 L/ha and a rotary atomiser at 3200 L/ha. The effect of oil spray on the citrus leafminer parasitoid Semielacher petiolatus (Girault) (Hymenoptera: Eulophidae) was inconsistent. Improved droplet deposition and coalescence may enhance the coverage of new growths and increase the efficacy of oil spray for protection of plants from oviposition.     

The effect of air support on droplet characteristics and spray drift

Air assistance on field sprayers creates a forced airstream under the spray boom which blows the spray droplets into the crop. The advantages of this relative new technique are less drift of spray droplets and the possibility to reduce the amount of pesticides and spray Liquid. The purpose of this work was to investigate the effect of air assistance on the characteristics of spray droplets and their driftability. Based on air velocity measurements on an air assisted field sprayer, a system of air assistance was developed in addition to a laser-based measuring set-up for the characterisation of spray droplets. With this set-up, the effect of air support on the droplet characteristics was investigated for different settings of the air assistance. The effect on spray drift was quantified based on field drift measurements. A reducing effect on the total amount of spray drift was demonstrated for the Hardi ISO F 110 02, F 110 03 and LD 110 02 nozzles with drift reduction factors a(d) of, respectively, 2.08, 1.77 and 1.53. The use of air support had no significant effect for the LD 110 03 nozzles on the total amount of spray drift. Comparing droplet size and drift results, it was found that air support has the highest impact on the amount of spray drift for the finer sprays by increasing droplet velocities. The effect of air support on droplet sizes is rather limited.     

Optimisation of sequence and orientation for used nozzles based on few, full boom distribution measurements

Most studies on uniformity of pesticide applications beneath agricultural spraying booms are based on the characteristics of nozzle spray patterns. When optimising general features (boom height, pressure, ...), average nozzle characteristics are used. In this research, individual nozzle characteristics are essential. When utilising slightly used nozzles, small irregularities in the nozzle spray distribution may be averaged out or amplified in the resulting full-boom distribution. A method is proposed to find whether the coefficient of variation (cv) of a field sprayer spray distribution could be optimised by altering the sequence and orientation of a given set of flat fan nozzles. A manageable model is used in order to quickly compute possible full-boom distributions (and cv's) with a given set of single nozzle spray distributions. The individual nozzle spray distributions are extracted from a limited series of full-boom spray distribution measurements (three in most cases) with randomised nozzle sequence and orientation by means of a Matlab optimisation algorithm.     

Spray Nozzles,Pressures, Additives and Stirring Time on Viability and Pathogenicity of Entomopathogenic Nematodes (Nematoda: Rhabditida) for Greenhouses

The objective of this study was to evaluate different strategies for the application of entomopathogenic nematodes (EPN). Three different models of spray nozzles with air induction (AI 11003, TTI 11003 and AD-IA 11004), three spray pressures (207, 413 and 720 kPa), four different additives for tank mixtures (cane molasses, mineral oil, vegetable oil and glycerin) and the influence of tank mixture stirring time were all evaluated for their effect on EPN (Steinernema feltiae) viability and pathogenicity. The different nozzles, at pressures of up to 620 kPa, were found to be compatible with S. feltiae. Vegetable oil, mineral oil and molasses were found to be compatible adjuvants for S. feltiae, and stirring in a motorized backpack sprayer for 30 minutes did not impact the viability or pathogenicity of this nematode. Appropriate techniques for the application of nematodes with backpack sprayers are discussed.     

Frontiers in alley cropping: Transformative solutions for temperate agriculture

Annual row crops dominate agriculture around the world and have considerable negative environmental impacts, including significant greenhouse gas emissions. Transformative land‐use solutions are necessary to mitigate climate change and restore critical ecosystem services. Alley cropping (AC)—the integration of trees with crops—is an agroforestry practice that has been studied as a transformative, multifunctional land‐use solution. In the temperate zone, AC has strong potential for climate change mitigation through direct emissions reductions and increases in land‐use efficiency via overyielding compared to trees and crops grown separately. In addition, AC provides climate change adaptation potential and ecological benefits by buffering alley crops to weather extremes, diversifying income to hedge financial risk, increasing biodiversity, reducing soil erosion, and improving nutrient‐ and water‐use efficiency. The scope of temperate AC research and application has been largely limited to simple systems that combine one timber tree species with an annual grain. We propose two frontiers in temperate AC that expand this scope and could transform its climate‐related benefits: (i) diversification via woody polyculture and (ii) expanded use of tree crops for food and fodder. While AC is ready now for implementation on marginal lands, we discuss key considerations that could enhance the scalability of the two proposed frontiers and catalyze widespread adoption.     

Weather limitations on the application of dinoseb-in-oil for cane vigour control in raspberry

Data on crop growth suggested that only 8 days are available for timely spraying of dinoseb-in-oil for control of cane vigour in raspberry in east-central Scotland. Crop records were linked with meteorological data to indicate the dates between which this 8-day period might fall. The meteorological data were then examined to assess the probability and likely duration of conditions suitable for spraying within the period when the crop is amenable to the spray treatment. The results indicated that unfavourable weather conditions may severely restrict the opportunities available for spray application by conventional equipment, the main limitation being high wind speed. The likelihood of rain after application putting the spray treatment at risk was found to be low. The infinitely compound Poisson distribution was found to be suitable for graduating the observed frequency distributions of suitable spraying conditions. Diagrams of frequency distributions were produced which can be used to assess the spraying capacity required to ensure timely application over the total area of a grower's plantations. It is suggested that the approach used in this investigation could be satisfactorily applied to a wider range of crops and spraying operations.     

Eradication of apple powdery mildew (Podosphaera leucotricha) with dormant season sprays of surface-active agents

selection of surfactants (5%, w/v, a.i.) representative of the three main ionic types eradicated Podosphaera leucotricha from buds on dormant apple trees, cvs Cox's Orange Pippin, Jonathan and Michelin. The pathogen was apparently killed without undue damage to buds, although a phytotoxic response in the form of staining of vascular tissue and some crop reductions were observed. Treatments applied with hand lances were equally effective at reducing infections of vegetative buds on terminals, on non-flowering spurs and flower buds. Indication of a positive correlation between the eradication of mildew from Cox's Orange Pippin trees and an increase in the incidence of apple canker (Nectria galligena) was found at Long Ashton, but this effect was negligible at sites in the West Midlands region. Efficacy of active formulations was reduced by rain soon after application or by a reduction in the concentration of applied material. Applications with a mist-blower were effective on the cv. Cox's Orange Pippin, but less so on the cv. Jonathan, while on both cultivars efficacy of a spray containing 5 % a.i. decreased in the order 2240:1120:560 1/ha. Anti-mildew activity was not associated with any particular chemical or ionic type of surfactant, and there was an indication that eradicant activity of alkyl phenol ethoxylates was related to their HLB value. The ecological and economic implications of the use of surfactants as fungicides are discussed.     

THE PHYLOGENETIC RELATIONSHIPS AMONG REQUIEM AND HAMMERHEAD SHARKS: INFERRING PHYLOGENY WHEN THOUSANDS OF EQUALLY MOST PARSIMONIOUS TREES RESULT

Abstract— Protein variation among 37 species of carcharhiniform sharks was examined at 17 presumed loci. Evolutionary trees were inferred from these data using both cladistic character and a distance Wagner analysis. Initial cladistic character analysis resulted in more than 30 000 equally parsimonious tree arrangements. Randomization tests designed to evaluate the phylogenetic information content of the data suggest the data are highly significantly different from random in spite of the large number of parsimonious trees produced. Different starting seed trees were found to influence the kind of tree topologies discovered by the heuristic branch swapping algorithm used. The trees generated during the early phases of branch swapping on a single seed tree were found to be topologically similar to those generated throughout the course of branch swapping. Successive weighting increased the frequency and the consistency with which certain clades were found during the course of branch swapping, causing the semi-strict consensus to be more resolved. Successive weighting also appeared resilient to the bias associated with the choice of initial seed tree causing analyses seeded with different trees to converge on identical final character weights and the same semi-strict consensus tree.
The summary cladistic character analysis and the distance Wagner analysis both support the monophyly of two major clades, the genus Rhizoprionodon and the genus Sphyrna. . The distance Wagner analysis also supports the monophyly of the genus Carcharhinus . However, the cladistic analysis suggests that Carcharhinus is a paraphyletic group that includes the blue shark Prionace glauca .     

Effects of site and fruit size on the composition of avian frugivore assemblages in a fragmented Afrotropical forest

Factors influencing the interaction between fruiting trees and their frugivorous seed dispersers in fragmented Afrotropical landscapes are poorly known. With the use of Mantel statistics we analysed assemblages of frugivorous birds on 58 individual trees belonging to 11 species growing in seven Kenyan cloud forest fragments. Overall, frugivores showed little specialization on particular trees. Fruit size explained a substantial amount of the variation in frugivore assemblages among different tree species at the same site. In addition, frugivore assemblages on conspecific trees were significantly more similar when the trees occurred at the same site. This location effect was attributable to the different sites and forest fragments (of different sizes and disturbance levels) varying in the densities and composition of their avian frugivores, vegetation composition and tree fruiting phenologies. It was consolidated further by the low mobility of most of these avian frugivores, particularly their reluctance to cross between forest fragments. Habitat disturbance and fragmentation may therefore have affected fruit selection, with implications for both seed dispersal and regeneration.     

Effect of natural windbreaks on drift reduction in orchard spraying

In the Netherlands windbreaks are commonly grown to protect orchards against wind damage and to improve micro-climate. Natural windbreaks of broad-leaved trees can also reduce the risk of surface water contamination caused by spray drift during orchard spraying. Spray drift from pesticide applications is a major concern in the Netherlands, especially drift into water courses. So far, several drift reducing measures have been accepted by water quality control organisations and the Board for the Authorization of Pesticides (CTB), e.g. presence of a windbreak (i.e. 70% drift reduction at early season and 90% drift reduction at full leaf, respectively before and after first of May). From the experiments it was concluded that the risk of drift contamination is high during the early developmental stages of the growing season. The 70% drift reduction at early season as determined in previous experiments, appears to be valid only for windbreaks with a certain degree of developed leaves. At full leaf stage 80-90% drift reduction by the windbreak was measured. The use of evergreen windbreaks or wind-break species that develop in early season can reduce the risk of drift contamination considerably. Also, the combination of drift reducing methods, such as one-sided spraying of the last tree row and a windbreak is an effective method to reduce spray drift in the Netherlands in early season.     

Mycorrhizas in agroforestry: spread and sharing of arbuscular mycorrhizal fungi between trees and crops: complementary use of molecular and microscopic approaches

The spread of arbuscular mycorrhizal (AM) fungi from tree to crop roots was examined by molecular and microscopic methods in a glasshouse study. Growth of Calliandra calothyrsus Meissner trees inoculated with isolates of the AM fungi Glomus etunicatum Becker and Gerdemann and Gigaspora albida Schenck and Smith was monitored over an 18-month period. Three successive ‘intercrops’ of beans or maize were sown at 25, 50 and 75 cm distances from the tree and harvested during this period. At each crop harvest, the distribution of tree and crop roots and the spread of the inoculant fungi were determined using traditional microscopic methods and fungal specific primers. Both inoculants greatly improved the growth of the trees and colonization spread to the crops once the trees were 6 months old. However, benefits of inoculation to crop growth were not observed due to increased competition from the larger inoculated trees growing in a restricted soil volume. Of the two inoculant fungi, Glomus etunicatum appeared to be more mobile as it spread more rapidly, formed higher levels of colonization at increasing distances from the tree and was responsible for most of the mycorrhizal cross-contamination. In contrast, colonization of tree and crop roots by Gigaspora albida was higher nearest the tree. This work demonstrated the benefits of mycorrhizal fungus inoculation for tree growth and confirmed that trees and crops share the same AM fungi. Trees may therefore act as reservoirs of mycorrhizal fungi, either inoculant or indigenous, for surrounding crops or other annual vegetation. It was also shown that tree pruning, the normal practice in agroforestry systems, did not reduce mycorrhizal colonization or prevent spread to crops. However, the slow rates of inoculant spread found here suggest that it may take years before inoculants benefit the growth of crops sown several metres from the tree. The work also demonstrated that microscopic quantification of mycorrhizal colonization and the use of molecular probes to identify specific fungi within roots can complement each other effectively. Molecular probes were more sensitive at detecting mycorrhizal fungi than microscopic methods, but did not discriminate between full mycorrhizal structures and traces of hyphae.     

Limitation of point source pesticide pollution: results of bioremediation system

Groundwater and surface water is at risk of contamination from the use of some agricultural pesticides. In many circumstances pesticide contamination of water resources is more likely to result from point sources than from diffuse sources following approved application to crops in the field. Such point sources include areas on farms where pesticides are handled, filled into sprayers or where sprayers are washed down. To overcome this way of contamination different kind of bio-remediation systems are nowadays in development. In Flanders, Belgium two pilot plants of bioremediation systems for the in situ retention and/or degradation of pesticides were installed. Both systems were based on the Phytobac concept, a watertight excavation filled with straw, peat, compost and soil. The channel was made in the bottom from plastic foil. All kinds of spray rests were captured by the phytobacs. This study focuses on what level pesticides leach, bio-degrade or are retained by the filling of the phytobac. The soil-properties of the filling were investigated. Pesticide tracers were added for monitoring to both phytobacs. Soil and water samples were taken during one year. Pesticides are retained at least for one month by the filling of the phytobac. Almost no pesticide leached out. In winter hardly any pesticide degradation was observed in the filling of the phytobac. In summer no detectable pesticides were still left in the phytobacs.     

Inequality of size and size increment in Pinus banksiana in relation to stand dynamics and annual growth rate

BACKGROUND AND AIMS: Changes in size inequality in tree populations are often attributed to changes in the mode of competition over time. The mode of competition may also fluctuate annually in response to variation in growing conditions. Factors causing growth rate to vary can also influence competition processes, and thus influence how size hierarchies develop. METHODS: Detailed data obtained by tree-ring reconstruction were used to study annual changes in size and size increment inequality in several even-aged, fire-origin jack pine (Pinus banksiana) stands in the boreal shield and boreal plains ecozones in Saskatchewan and Manitoba, Canada, by using the Gini and Lorenz asymmetry coefficients. KEY RESULTS: The inequality of size was related to variables reflecting long-term stand dynamics (e.g. stand density, mean tree size and average competition, as quantified using a distance-weighted absolute size index). The inequality of size increment was greater and more variable than the inequality of size. Inequality of size increment was significantly related to annual growth rate at the stand level, and was higher when growth rate was low. Inequality of size increment was usually due primarily to large numbers of trees with low growth rates, except during years with low growth rate when it was often due to small numbers of trees with high growth rates. The amount of competition to which individual trees were subject was not strongly related to the inequality of size increment. CONCLUSIONS: Differences in growth rate among trees during years of poor growth may form the basis for development of size hierarchies on which asymmetric competition can act. A complete understanding of the dynamics of these forests requires further evaluation of the way in which factors that influence variation in annual growth rate also affect the mode of competition and the development of size hierarchies.     

Neighbourhood analyses of tree seed predation by introduced rodents in a New Zealand temperate rainforest

House mice Mus musculus and other introduced rodents represent a novel source of predation on tree seeds in New Zealand forests. In the northern temperate forests where these rodents are native, spatial and temporal variation in tree seed production can result in dramatic fluctuations in the distribution and abundance of seed predators, with subsequent feedbacks on the distribution and abundance of seedlings. We use neighbourhood models to examine variation in rodent predation on seeds of 4 tree species of the temperate rainforests of New Zealand as a function of 1) spatial variation in local canopy composition and 2) spatial and temporal variation in mouse activity. We placed seeds throughout mapped stands of mixed forests in alluvial valley bottoms and on elevated marine terraces in the Waitutu Forest, South Island. The risk of predation on seeds of 2 dominant canopy trees – rimu Dacrydium cupressinum and mountain beech Nothofagus solandri var . cliffortioides – peaked in neighbourhoods dominated by those species and by silver beech N. menziesii , particularly in a year of plentiful seed rain from these species. The risk of predation on rimu and beech seed was also related to measures of local mouse activity. These relationships suggest that the highest local abundance of mice was concentrated in rimu and beech neighbourhoods because of the food provided by seed rain from those trees. Predation on seed of miro Prumnopitys ferruginea , which is eaten by rats but not mice, was low in rimu neighbourhoods and where mouse activity was high. These patterns may reflect spatial segregation in the activity of rats versus mice within stands. Our results suggest that the spatial distribution of canopy trees translates into predictable patterns of variation in mouse activity and seed predation. Heterogeneity in rodent activity and seed predation within stands may have important implications for tree population dynamics.     

The Tropical Forests of Southern China and Conservation of Biodiversity

Species-rich tropical forests once occurred along much of China’s southern border, from southeastern Xizang (Tibet) and southern Yunnan to southwestern Guangxi, southern Taiwan and Hainan, mainly south of 22°30’N latitude. These Chinese forests are similar to Southeast Asian lowland tropical forests in their profiles and physiognomic characteristics, floristic composition and species richness. Studies of these southern forests in China are reviewed. Complete vegetation studies on the physiognomy and floristic composition have been done in southern Yunnan, Hainan and southwestern Guangxi. Forest fragmentation, dispersal patterns of trees, and the maintenance, population dynamics, phylogenetic community structure, tree functionality and phylogenetic diversity and conservation of these tropical Chinese forests have also been studied. Major changes in land use in China have resulted in an increase in rubber and Eucalyptus plantations and a decrease in the extent of southern forests. The direct results have been fragmentation and loss of biodiversity. The underplanting of economic crops in native forests also threatens to destroy saplings and seedlings, causing the forest to lose its regenerative capacity. Limiting further expansion of monoculture tree plantations, restricting underplanting, and promoting multi-species agroforestry systems are needed in China to conserve the biodiversity of its forests.