Foliar Analysis Research Articles

Foliar sampling time and critical level diagnosis of nutrients for blackberry

Foliar analysis makes it possible to accurately diagnose nutritional deficiencies, which are difficult to be identified by soil analysis or visual diagnosis. The moment to carry out the foliar analysis is essential so that the results can be used for fertilizing, with the results from the soil analysis, to ensure the growth of the plant. Thus, this study aims to assess the best foliar sampling time and to propose the critical levels of nutrients for the nutritional diagnosis of the blackberry. The soil in the experimental area is Typic Quartzipsamment, which has 83% sand, 10% clay and 7% silt. The experiment was done in an orchard with six and seven years old blackberries (Rubus spp.), ‘Brazos’, ‘Guarani’, ‘Tupy’ and ‘BRS Xavante’. Foliar sampling was done during vegetative growth, beginning of flowering and fruiting of plants. The determination of the best sampling time has been evaluated from the foliar nutrient content and the productivity. Critical nutrient levels were proposed with the methodology of reduced normal distribution. The best moment for foliar sampling of blackberry to evaluate nutritional status is at the beginning of flowering. The critical levels proposed for macronutrients (g.kg−1) are 25.5 for N; 2.0 for P; 11.2 for K; 2.9 for Ca; 0.3 for Mg and 2.1 for S, and for micronutrients (mg.kg−1), 15.5 for B; 9.7 for Cu; 79.6 for Fe; 116.4 for Mn and 22.9 for Zn. These levels for P, K, Ca, Mg, S and B are below the ranges considered suitable for blackberry.

Phosphate, potassium and magnesium fertilization on oil palm productivity: 12 years of monitoring in the Brazilian Amazon

Despite the importance of oil palm, there is little research related to increasing the productivity of the palm under Brazilian conditions, especially in the Amazon region. The objective of the study was to evaluate the effect of phosphorus (P), potassium (K) and magnesium (Mg) on oil palm production during the productive period in the Brazilian Eastern Amazon. The experimental area consisted of 12.64 ha with 1824 trees, spacing was in equilateral triangle (9.00 m between trees and 7.80 m between rows). The adopted design was in randomized blocks, in a factorial scheme 4 × 3 × 2, consisting of four doses of P, three doses of K and two doses of Mg. The evaluation of the experiment began at the 6th year of plant age, and the components of oil palm productivity were evaluated: numbers of fruit bunches per tree (NB), fresh fruit bunches weight per tree (BW), bunch productivity (BP) until the 12th year of plant age. Foliar analysis was performed for the nutrients N, P, K, Ca, Mg and Boron (B). The application of phosphate source promoted increases in NB, BW and BP of oil palm during all the years evaluated. Increasing the K-fertilizer dose implied increases in BW and BP in oil palm trees during all years. The application of Mg-sulfate does not promote an increase in the yield components and foliar Ca and Mg concentration of oil palm, from the 6th to the 12th year of development.

PLANT ANALYSIS BASED ON THE DRIS SYSTEM: PROGRAMMING INTERFACE WITH A CASE STUDY IN PLANTAIN CROP (Musa AAB)

The Diagnosis and Recommendation Integrated System (DRIS) is a tool to evaluate the nutritional status and obtain fertilizer recommendations of several crops. Unlike other methods, DRIS works directly with farmer’s information, focusing on understanding the nutritional balance of the crop. However, the selection of indexes is long and time-consuming. The objective of this work was to develop an algorithm to estimate reference and DRIS indexes for crops in order to facilitate the use of the DRIS methodology. The construction of the algorithm included four stages, (1) theoretical bases, (2) conceptual model design, (3) algorithm implementation, and (4) validation. For a database of crop yield and foliar analyses, the developed algorithm is divided into two subsets (high and low yield), estimating nutrient ratios and variability. For leaf sample diagnosis, the algorithm compares nutritional balance with highy-ield population, generating DRIS indexes numerically and graphically. A nutrient is imbalanced if its DRIS index in the graph is outside the whiskers. The efficiency and operability of the algorithm was tested with foliar analyses of fifty plantain crops distributed in two subregions of the Antioquia Department, Colombia. The developed procedure allowed determining quantitative and graphical information of the nutrient balance in foliar samples.

Nitrogen dose and sowing density in pea (Pisum sativum L.) crops, to obtain higher yields in Barranca [Dosis de nitrógeno y densidad de siembra del cultivo de arveja (Pisum sativum L.), para obtener mayor rendimiento en Barranca

The research deals with nitrogen doses and sowing densities in peas. The objective was to determine which nitrogen dose and planting density obtained the highest yield. The methodology is based on applied research; Therefore, the statistical model of the Completely Random Block Design was used, which consisted of 3 blocks and 6 treatments. The doses were applied at 17 days 1/2 N, 100% P2O5 and 100% K2O and 62 days after sowing 1/2 N, it was evaluated from sowing to harvest and the data were processed by analysis of variance of two factors and Duncan, took leaf samples for foliar analysis and determined the total amount of nitrogen used. It was determined that T5 stood out in stem length with 128.42 cm, commercial yield with 12.53 tn/ha, T4 in weight of pods with 620 g, number of pods per plant with 48, T6 in nitrogen concentration with 6.60 g/ 100 g of dry matter and T5 in the amount of nitrogen used with 154.3 kg/ha that obtained the highest yield. It is concluded that the higher dose of nitrogen and less distance that is T5 obtained higher performance exceeding by 24.52% in relation to T1.

Fertilization with different soil types in viticulture: a three-year experience in Trentino Alto Adige

The work aimed at investigating the impact of various good quality soils of on vineyard productivity. Manure matured with a fast and controlled process and compost obtained from digestate of an organic fraction of municipal solid waste (OFMSW) were applied one time on a grapevine row, in two CAVIT vineyards. A physico-chemical characterization of the soils was carried out and biological quality indices QBS-ar (Arthropodological Biocenosis) were calculated. The vegeto-productive monitoring was performed by foliar nutrients analysis and measuring NDVI and SPAD indices. The organic source had a significant fertilizing effect, especially manure, which determined a nutrient increase in soil (P, K and Mg), a rise in photosynthetically active biomass, available nitrogen and potassium in plants. The effects on the biological community of soils and musts quality were negligible. The use of soil improvers could be an efficient strategy for the nutrition of not vigorous vineyards, which do not require high nitrogen inputs.

Valores de referência nutricional para bananeira ‘BRS Platina’ em solos de fertilidade construída

ABSTRACT Reference values of leaf nutrient contents are essential for nutritional assessment of plants. The objective was to establish nutritional reference values for ‘BRS Platina’ banana in improved fertility soil, using the sufficiency range (SR), border Line (BL) and mathematical chance (MCh) methods, in addition to the critical level obtained by the reduced normal distribution (CLz). The study was carried out in Guanambi-BA, considering nutrient contents and yields of an experiment arranged in randomized blocks, 5 x 6 factorial scheme, with five doses of K2O (0, 200, 400, 600 and 800 kg ha-1) supplied with fertilizers for organic management and six sampling times (210; 390; 570; 750; 930 and 1,110 days after planting), totaling 90 plots. Plots with high yield, ≥ 38.40 t ha-1, formed the reference population and plots with yield ≥ 47.43 t ha-1 formed the reference subpopulation. There was convergence between the optimal values obtained by the methods evaluated. Therefore, the reference values adjusted by the SR, BL, MCh and CLz methods can be used with assertiveness to interpret the foliar analysis of the ‘BRS Platina’ banana in improved fertility soils. Furthermore, among these, MCh stands out as it provides narrower optimal ranges.

Biostimulant Effects of Micro Carbon Technology (MCT®)-Based Fertilizers on Soil and Capsicum annuum Culture in Growth Chamber and Field

Due to the environmental issues that conventional fertilization is causing, biostimulants are proposed as environmentally friendly alternative for crop nutrition in agriculture. The aim of this study was to determine the effects of new Micro Carbon Technology (MCT®) fertilizers with biostimulant activity based on humic acids biologically digested from leonardite on pepper plant growth in three different soils with different textures. The assays were performed under controlled conditions in a growth chamber and in commercial greenhouses in Spain. The effects on soil were analyzed after the addition of the fertilizers by microbial respiration and enzymatic activities (hydrolase, dehydrogenase and urease). For the plant assays, biometric parameters (fresh weight and fruit hardness) and foliar analysis (chlorophyll indices and nutrients) were evaluated. Under controlled conditions, the use of these biostimulants resulted in a greater soil microbial activity in a 24 h interval with increased soil enzymatic activity. In plants, a positive correlation was found between fertilizers with biostimulant activity and Dualex indices of leaves and content of macronutrients Ca and Mg. In commercial greenhouses, the fertilizers with biostimulant activity strongly depended on the soil texture. In conclusion, these products have real potential to replace conventional fertilizers in commercial production fields.

Quality and Yield of Lettuce in an Open-Air Rooftop Hydroponic System

In this study, the yield and growth performance of lettuce in an open-air rooftop hydroponic system were investigated. Lettuce was grown in a closed recirculating nutrient film technique (NFT) unit using a standard nutrient solution (NS). Yield, fresh weight, and nutrient content in the leaf tissue of the harvested lettuce were measured. The results were compared with the results obtained in indoor hydroponic lettuce growth with artificial lightning. Despite strong winds during the growth period, 25% of the total lettuce heads weighed twice the marketable weight; however, 25% of the total lettuce heads were below the marketable weight. A more efficient nutrient uptake was indicated by the lettuces in the rooftop system compared with the uptake in the indoor system. Foliar analysis revealed a higher content of all nutrients in the leaves of rooftop hydroponic lettuce compared with indoor hydroponic lettuce. This study suggests that hydroponic rooftop-grown lettuce can be competitive with their indoor counterparts if the rooftop hydroponic system is protected from extreme weather conditions.

Fertilización de dos grupos genéticos de Pinus patula Schiede ex Schltdl. & Cham. en un ensayo de progenies de cuatro años

Introduction: Genetic improvement and nutritional management are used to increase productive capacity. Objective: To analyze the effect of traditional and controlled-release fertilizers, as well as the way to define the doses (technically or empirically), on growth of 20 tree families of Pinus patulaSchiede ex Schltdl. & Cham. Materials and methods: Four fertilization treatments were applied: 1) control; 2) “technical”, based on foliar analysis; 3) controlled release (18-6-12 + 2CaO + 3.5 Mg + 2.1 Si + microelements); and 4) mixture of agricultural fertilizers in nutrient concentrations similar to the controlled-release treatment. Height, diameter, biomass index, number of whorls, leaf mass, and growth initiation and cessation were evaluated in a group of 10 superior and 10 inferior three-year old families in Chignahuapan, Puebla. Data were analyzed with the MIXED procedure of SAS. Results and discussion: Trees showed no significant differences in growth, biomass production and growth initiation by fertilization effect, but showed significant differences by genetic quality (P ≤ 0.05). The genotype*fertilization interaction was significant; after one year of controlled-release fertilizer application, inferior genotypes had the highest values of relative rates of biomass production, diameter at root collar and height. Conclusions: Controlled-release fertilizers at appropriate doses and environmental conditions are a viable option to promote growth of young P. patula trees in the field.

Estimation of Diagnosis and Recommendation Integrated System (DRIS), Compositional Nutrient Diagnosis (CND) and Range of Normality (RN) Norms for Mineral Diagnosis of Almonds Trees in Spain

To ensure good fertilization, it is necessary to know the optimum nutrient levels for each crop. The most common method for obtaining this information for almond trees is to perform a foliar analysis coupled with the use of interpretive tools such as the traditional range of normality. However, currently, there are other, more sophisticated methods such as the DRIS (Diagnosis and Recommendation Integrated System) and the CND (Compositional Nutrient Diagnosis) which take into account the relationship between nutrients. However, little information is available with respect to these methods in the case of almond trees. In the present work, 288 samples of three contrasting varieties of almond were analyzed—Ferraduel, Ferragnes, and Garrigues (Prunus dulcis, Mill.)—corresponding to bi-weekly sampling between the months of May and September. Leaf analysis data, run with different mathematical and statistical models, lead to knowledge of the optimum period for harvesting samples and the determination of the ranges of normality and norms of DRIS and CND for the Ferraduel, Ferragnes, and Garrigues varieties. Data gained from the leaf nutrient content reported that the best season to harvest and interpret leaf samples was July. In addition, Ferraduel and Ferragnes had higher N, P, and K (2.22, 0.14, and 1.04 mg Kg−1 dw, respectively) than Garrigues (2.00, 0.09. 0.67 mg Kg−1 dw). The norms obtained with the leaf mineral data showed similar values between the Ferraduel and Ferragnes varieties but different values for Garrigues variety. Therefore, Garriges had the highest N/P, N/K, P/K, and P × Mg norms in the DRIS method and the highest VN and VCa norms in the CND method.

Effect of phosphorus doses to obtain higher yields in the cultivation of garlic (Allium sativum L.), at the district of Barranca [Efecto de las dosis de fósforo para obtener mayor rendimiento en el cultivo de ajo (Allium sativum L.), en el distrito de Barranca

The research deals with phosphorus fertilization to obtain higher yields in garlic cultivation. The objective was to determine the appropriate dose of foliar phosphorus fertilization, to obtain a higher yield in garlic cultivation. The methodology is based on applied and experimental research; Therefore, the Completely Random Block Design was used, composed of 4 blocks and 5 treatments which were T1 = 00, T2 = 250, T3 = 500, T4 = 750, T5 = 1000 mL of phosphorus (Wuxal phosphorus)/200 L. water and were applied 15, 30 and 45 days after sowing. They were evaluated from sowing to postharvest and the data were processed with analysis of variance and Duncan. Likewise, phosphorus concentrations in leaves were analyzed. The results determined that T4 stood out in stem length with 35.28 cm, commercial yield with 11.208 tn/ha, bulb weight with 34.28 g, number of bulblets with 13 and foliar analysis highlighted T5 with 0.48 g/100 g d.s. (dry material). It is concluded that the T4 dose with 750 mL of phosphorus (Wuxal Phosphorus)/200 L of water increased 13.01% in yield in relation to T1; being significant.

Hydroponic Lettuce Cultivation Using Organic Nutrient Solution from Aerobic Digested Aquacultural Sludge

The aim of this study was to demonstrate how aquacultural sludge can be processed and utilized as an organic nutrient solution (ONS) for hydroponic lettuce production. By using a previous developed method, approximately 80% of the processed sludge was reclaimed as a clear, nutrient-rich solution. The performance of the recovered nutrient solution on lettuce growth was assessed in a nutrient film hydroponic system. The results were compared to the results obtained using a conventional nutrient solution (CNS). Yield, fresh weight, water consumption, and nutrient and heavy metal content in leaf tissue were measured. In spite of a 16% lower average fresh weight obtained in ONS compared to the weight obtained in CNS, there was no statistical difference of the yield of lettuce among the two nutrient solutions. After the cultivation period, 90% of the lettuce heads grown in ONS exceeded the marked weight of 150 g. Foliar analysis revealed a similar or higher content of all nutrients, except of magnesium and molybdenum in the leaves of lettuce grown in the ONS compared to lettuce grown in the CNS. This study shows that nutrients recovered from aquacultural sludge can be utilized as fertilizer, thereby reducing the dependency on mineral fertilizer in hydroponic and aquaponic systems.

The Effect of Different Organic Foliar Fertilization on Physiological and Chemical Characters in Hop (Humulus lupulus L., cv Cascade) Leaves and Cones

Background: Hop cultivation requires an abundant quantity of nutrients to reach higher cone yield and quality. The aim of this work was the evaluation of different fertilization plans to obtain an improvement in product quality. Methods: Foliar analysis, anatomical analysis through the use of light microscope and SEM; physiological measurements through atLEAF, Handy PEA and spectrophotometry, were carried out to determine chlorophyll content, carotenoids and photosynthetic efficiency in two periods (t1, t2) for four experimental treatments and a Control (Treat 1, Treat 2, Treat 3, Treat 4, Untreat). Leaf texture (texture analyzer), color (colorimeter), DPPH activity (spectrophotometer), bitter acid content (HPLC-UV) and essential oil yields (steam distillation) and cone yields were measured. Results: Treat 2 showed the best performance: (i) in leaves, in terms of texture, chlorophyll content and color; (ii) in cones, with 6.98% of alpha acids, 1.78% of oil yield and 3.55 kg of fresh cones per plants. Conclusion: The fertilization plans caused alteration in micro and macro elements content in hop leaves and in the composition of hop cones. In our conditions, the best fertilization plan, in terms of cone productivity and quality, was Treat 2, highlighting the value of a customized organic foliar fertilization plan for hop cultivation.

The use of near infrared spectroscopy to predict foliar nutrient levels of hydroponically grown teak seedlings

Due to a combination of durability, strength, and aesthetically pleasing color, teak ( Tectona grandis L.f.) is globally regarded as a premier timber species. High value, in combination with comprehensive harvesting restrictions from natural populations, has resulted in extensive teak plantation establishment throughout the tropics and subtropics. Plantations directly depend on the production of healthy seedlings. In order to assist growers in efficiently diagnosing teak seedling nutrient issues, a hydroponic nutrient study was conducted at North Carolina State University. The ability to accurately diagnose nutrient disorders prior to the onset of visual symptoms through the use of near infrared (NIR) technology will allow growers to potentially remedy seedling issues before irreversible damage is done. This research utilized two different near infrared (NIR) spectrometers to develop predictive foliar nutrient models for 13 nutrients and then compared the accuracy of the models between the devices. Destructive leaf sampling and laboratory grade NIR spectroscopy scanning was compared to nondestructive sampling coupled with a handheld NIR device used in a greenhouse. Using traditional wet lab foliar analysis results for calibration, nutrient prediction models for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sulfur (S), copper (Cu), molybdenum (Mo), magnesium (Mg), boron (B), calcium (Ca), manganese (Mn), iron (Fe), sodium (Na), and zinc (Z) were developed using both NIR devices. Models developed using both techniques were good for N, P, and K (R2 > 0.80), while the B model was adequate only with the destructive sampling procedure. Models for the remaining nutrients were not suitable. Although destructive sampling and desktop scanning procedure generally produced models with higher correlations they required work and time for sample preparation that might reduce the value of this NIR approach. The results suggest that both destructive and nondestructive sampling NIR calibrations can be useful to monitor macro nutrient status of teak plants grown in a nursery environment.

Rainfall is the major driver of plant Si availability in perudic gibbsitic Andosols

The amount of water available to leach solutes from soil is one of the major features determining mineral weathering, mineral neoformation and soil properties. It affects the fate of dissolved silicon (Si), which may follow four routes: leaching, mineral synthesis, adsorption, uptake by plants forming phytoliths. Here, we quantify the reservoirs of bioavailable Si and phytolithic Si in topsoils (0–20 cm) from wet tropical Andosols along a climosequence where mean annual rainfall (MAR) increases from 2650 to 4400 mm with increasing altitude (65–375 m asl) in Basse-Terre, Guadeloupe. We assessed bioavailable Si through CaCl2 extraction in soil, and foliar analysis in banana plants. We evaluated the pool of phytolithic Si through Na2CO3 extraction and heavy liquid separation. The Na2CO3 extraction was performed on both the bulk soil and oxalate–treated soil (ox-Na2CO3) cleared of its amorphous aluminosilicates. The Andosols have reached an advanced weathering stage. Their secondary products included (Al, Fe)–humus complexes, ferrihydrite, gibbsite, poorly crystalline Al hydroxide, and aluminous allophanic substances. The contents of organic C, metal-humus, ferrihydrite and gibbsite increased in soils in the wettest conditions (>3000 mm) whereas allophane content concomitantly decreased. Silicon leaf content varied little (3.8–5.3 g kg−1), but slightly decreased with increasing MAR (r = −0.48). Bioavailable Si content in soil decreased from 63 to 12 mg kg−1 with increasing MAR (r = −0.92), and was strongly correlated (r = +0.95) to that of phytolithic Si as assessed after ox-Na2CO3 extraction, linked to fresh, labile phytoliths. The Si/Al atomic ratio of the ox-Na2CO3 extract regularly decreased from 1.06 to 0.37 with increasing MAR, hence corroborating strongest desilication in soils in the wettest conditions. In these highly leached, gibbsitic Andosols, rainfall is thus the major driver of plant Si availability.

Plot-Based Classification of Macronutrient Levels in Oil Palm Trees with Landsat-8 Images and Machine Learning

Oil palm crops are essential for ensuring sustainable edible oil production, in which production is highly dependent on fertilizer applications. Using Landsat-8 imageries, the feasibility of macronutrient level classification with Machine Learning (ML) was studied. Variable rates of compost and inorganic fertilizer were applied to experimental plots and the following nutrients were studied: nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg) and calcium (Ca). By applying image filters, separability metrics, vegetation indices (VI) and feature selection, spectral features for each plot were acquired and used with ML models to classify macronutrient levels of palm stands from chemical foliar analysis of their 17th frond. The models were calibrated and validated with 30 repetitions, with the best mean overall accuracy reported for N and K at 79.7 ± 4.3% and 76.6 ± 4.1% respectively, while accuracies for P, Mg and Ca could not be accurately classified due to the limitations of the dataset used. The study highlighted the effectiveness of separability metrics in quantifying class separability, the importance of indices for N and K level classification, and the effects of filter and feature selection on model performance, as well as concluding RF or SVM models for excessive N and K level detection. Future improvements should focus on further model validation and the use of higher-resolution imaging.

Balanced mixture of biochar and synthetic fertilizer increases seedling quality of Acacia mangium

Biochar is a charcoal-like substance produced by pyrolisis of organic material from agricultural and forestry wastes, that can improve soil and substrates physical and chemical properties in the field and in plant nurseries. Despite some studies showing the advantages of its use in forestry nurseries, other studies show that biochar effects on seedling growth and quality are variable, and depends on the specific properties of the biochar and the particular species response to it. The objective of this study was to evaluate, through the analysis of the substrate and plant measurements, the effect of biochar produced from Acacia mangium Willd wood residues on the production of the same species seedlings. An experiment with complete factorial design, in a completely randomized arrangement, was established, with 9 treatments resulting from the combination of A. mangium biochar (BAM) and synthetic fertilizer (FS), with 3 dose levels for BAM: 0, 40, and 80 ton · ha −1 and 3 levels for the FS: 0% 50% and 100% of common fertilizer practice in the studied region of Colombia. The quality of the seedlings was estimated using the Dickson index (DQI), which considers the size and biomass allocation of the plant. The addition of BAM + FS increased the cationic exchange capacity, nitrogen, phosphorus, organic matter and carbon in the substrate without modifying the pH or the concentrations of calcium and potassium. Foliar analysis showed an increase in these cations in BAM treatments. An increase of over 130% was found in the DQI of seedlings with BAM + FS, but an intermediate dose of both elements was required to achieve this improvement in seedling quality. Neither of the two fertilizer alternatives alone resulted in good seedling quality.

Augmenting Nutrient Acquisition Ranges of Greenhouse Grown CBD (Cannabidiol) Hemp (Cannabis sativa) Cultivars

There is a growing interest in the production of hemp for the extraction of cannabidiol (CBD) due to reported therapeutic benefits. Recent policy reform has permitted state hemp pilot programs, including the land grant research institutions, the ability to investigate the potential of growing and harvesting Cannabis sativa plants (≤0.3% tetrahydrocannabinol) for these purposes in the U.S. There are vast gaps of knowledge regarding the fertility requirements of hemp cultivars grown in a horticultural production setting for floral attributes such as the cannabinoid constituents. Foliar tissue analysis provides an avenue to determine adequate ranges for nutrient uptake and estimating fertilizer requirements prior to visual symptoms of deficiency or toxicity. To facilitate a survey range of elemental nutrient acquisition in hemp cultivars propagated for CBD production, foliar analysis was executed using the most recently mature leaves (MRML) of mother stock plants. All plants were maintained in the vegetative stage for twelve weeks, prior to initiation of cutting for clone harvesting. A total of thirteen cultivars were utilized to broaden previously reported baseline survey ranges. Significant differences were found among all thirteen cultivars in accumulation of both micro and macro essential nutrients, widening the range of the fertility requirements of Cannabis plants grown in this production model for CBD harvesting.

Boron deficiency may be widespread in Brassica oleracea var. capitata L. in Lao Cai Province, North Western Vietnam

ABSTRACT Cabbage (Brassica oleracea var. capitata L.) is widely grown in the highlands of North Western Vietnam, and foliar analysis of 18 crops in the Bac Ha district, and 9 in the Sa Pa district of the Lao Cai Province, revealed low mean concentrations of boron (B, 15.6 mg kg−1), and copper (Cu, 4.8 mg kg−1). In three following field experiments, B treatments generally increased foliar B concentrations and growth, whereas Cu treatments affected neither growth nor the foliar Cu concentration. For the three experiments, the relative treatment yield within an experiment, and its foliar B concentration, define a critical concentration of 8–10 mg B kg−1. That is, B deficiency seasonally limits cabbage yields in Lao Cai Province, and liming increases the deficit. Soil applications of B and Cu are inexpensive and effective, but repetition should be justified by foliar analysis. Lastly, excess N was applied to more than half of the cabbage crops, with potentially deleterious impacts on shelf-life, human health, and the environment.

The potential role of aerial pesticide applications to control landscape-scale outbreaks of pests and diseases in British forestry with a focus on dothistroma needle blight

Abstract British forestry is threatened by numerous pests and diseases. This study investigated the potential for re-introduction of aerial pesticide applications for landscape-scale disease management. In North Scotland in 2013 and 2015, copper oxychloride was applied to Pinus sylvestris L. stands infected with Dothistroma septosporum (Dorogin) Morelet. Helicopters distributed ultra-low-volume (ULV) applications of product via Micronair rotary atomisers, following methods used against D. septosporum in P. radiata D. Don stands in New Zealand. Product deposition was quantified on paper catchers and in foliage, soil and water. Catchers 100 m beyond the plot boundaries intercepted 0.5 per cent of within-plot mean deposition. Foliar analysis revealed slightly elevated copper concentrations (+0.07 μg g−1 dw) 250 m outside plot boundaries. Copper in foliage and needle litter remained above background levels for 109 and 157 weeks after application, respectively, longer than recorded during New Zealand operations. Concentrations in the soil increased over 3 years’ monitoring, whilst deposition into water traps resulted in copper concentrations well within limits set by the Scottish Environmental Protection Agency. No deleterious impacts on vascular and non-vascular ground and canopy flora were recorded. Copper fungicide applications significantly reduced foliar infection at both sites but did not affect needle retention. Further ground-based trials will investigate the efficacy of other actives. In Britain, such aerial operations have not occurred for two decades: this study demonstrated aerial and ground teams have the necessary expertise for their re-introduction, whilst highlighting areas needing further optimization.