Defoliation Research Articles

Heatwaves do not limit recovery following defoliation but alter leaf drought tolerance traits.

As heatwave frequency increases, they are more likely to coincide with other disturbances like insect defoliation. But it is unclear if high temperatures after defoliation impact canopy recovery or leaf traits which may affect response to further stressors like drought. To examine these stressor interactions, we subjected defoliated (DEF) and undefoliated (UNDEF) oak saplings to a simulated spring heatwave of +10°C for 25 days. We measured gas exchange, leaf area recovery, carbohydrate storage, turgor loss point (ΨTLP ), and minimum leaf conductance (gmin ). During the heatwave, stem respiration exhibited stronger thermal acclimation in DEF than UNDEF saplings, while stomatal conductance and net photosynthesis increased. The heatwave did not affect leaf area recovery or carbohydrate storage of DEF saplings, but reflush leaves had higher gmin than UNDEF leaves, and this was amplified by the heatwave. Across all treatments, higher gmin was associated with higher daytime stomatal conductance and a lower ΨTLP . The results suggest defoliation stress may not be exacerbated by higher temperatures. However, reflush leaves are less conservative in their water use, limiting their ability to minimise water loss. While lower ΨTLP could help DEF trees maintain gas exchange under mild drought, they may be more vulnerable to dehydration under severe drought.

Beneficial effects of bunch-zone late defoliations and shoot positioning on berry composition and colour components of wines undergoing aging in an organically-managed and rainfed Sangiovese vineyard

In the context of climate change, where high temperatures are frequent in the first phases of ripening, protecting grapevine bunches from solar radiation is essential for preserving berry composition and wine colour. The effects of bunch-zone late defoliations (DEFs) and “semi-ballerina” shoot positioning (SB) on vine physiology and grape and wine quality of organic cv. Sangiovese wines during storage were assessed in two contrasting seasons (2013 and 2014). The treatments altered neither vine physiology (leaf photosynthetic activity and stomatal conductance, stem water potential) nor vine phenology, yield, budburst and fruitfulness. Defoliations imposed at post-veraison (DEF I) and pre-harvest (DEF II), but not shoot positioning imposed at post-veraison, enhanced the concentration of berry skin flavonols at harvest, compared to an untreated control. Late defoliations and SB did not change berry weight, anthocyanins, soluble solids, pH or titratable acidity at harvest. The severity of Botrytis bunch rot was assessed in both seasons. In 2013, it was negligible regardless of the treatment. In 2014 (characterised by higher rainfall and lower average temperatures than in 2013), late defoliations (DEF I and DEF II), especially DEF I, and SB to a minor extent, limited the severity of Botrytis bunch rot. The oenological benefits of late defoliations and shoot positioning were observed during wine storage. These canopy management practices positively influenced wine components (polymeric pigments; namely short polymeric pigments) that might have a marked effect on the final colour intensity, without altering the basic chemical characteristics of the wine. When choosing the timing for carrying out defoliation in order to improve grape quality and bunch rot containment, the meteorological conditions should be properly considered. Our results may contribute to providing further recommendations for canopy management for grape growers who produce organic Sangiovese wines that undergo aging.

Defoliation Change of European Beech (Fagus sylvatica L.) Depends on Previous Year Drought.

European beech (Fagus sylvatica L.) forests provide multiple essential ecosystem goods and services. The projected climatic conditions for the current century will significantly affect the vitality of European beech. The expected impact of climate change on forest ecosystems will be potentially stronger in southeast Europe than on the rest of the continent. Therefore, our aim was to use the long-term monitoring data of crown vitality indicators in Croatia to identify long-term trends, and to investigate the influence of current and previous year climate conditions and available site factors using defoliation (DEF) and defoliation change (ΔDEF) as response variables. The results reveal an increasing trend of DEF during the study period from 1996 to 2017. In contrast, no significant trend in annual ΔDEF was observed. The applied linear mixed effects models indicate a very strong influence of previous year drought on ΔDEF, while climate conditions have a weak or insignificant effect on DEF. The results suggest that site factors explain 25 to 30% DEF variance, while similar values of conditional and marginal R2 show a uniform influence of drought on ΔDEF. These results suggest that DEF represents the accumulated impact of location-specific stressful environmental conditions on tree vitality, while ΔDEF reflects intense stress and represents the current or recent status of tree vitality that could be more appropriate for analysing the effect of climate conditions on forest trees.

Effects of Damaged Levels and Pruning of Peach and Japanese Apricot Trees by Hailstorms on the Performance

Defoliation (DF) on peach (Prunus persica L.) and Japanese apricot (Prunus mume Sieb. et Zucc.) trees caused by a hailstorm in 2017, year 1, was investigated for its effects on growth and fruit yield in South Korea over four years, comparing with recovery effects of the DF trees treated with repeated immediate pruning (IP) right after the storm. Treatments included 0–10, 10–40, 40–70, and 70–100% of DF trees, with 0–10, 10–40, 40–70, and 70–100% of DF + IP trees. The hailstorms increased the damages to shoots for peaches and to shoots and scaffold for Japanese apricot trees in year 1, with fruit yield reduced more than 80% observed on 10–100 DF of both fruit species. The IP treatment increased the number of new shoots in years 2–4 but reduced shoot length and diameter of peach and Japanese apricot trees. Tree canopy in years 2–4 was reduced on 40–100 DF of peach trees and on 70–100 of DF and DF + IP of Japanese apricot trees. The 40–100 DF Japanese apricot trees resulted in a fruit yield index of less than 90% for years 2–4, which was observed on 40–100 DF+IP trees only in year 2 due to balanced tree vegetative and reproductive growth.

Avaliação da contaminação parasitária em folhas de alface da horta ao consumidor final

A contaminação vegetal pode acontecer em vários processos, desde a irrigação, adubação, coleta, transporte, armazenamento, comercialização e até mesmo a contaminação desencadeada pelas mãos de manipuladores e consumidores. Para minimizar e/ou anular essa contaminação é necessário adesão de medidas que melhorem a higienização do vegetal. Neste estudo foram utilizadas 27 amostras de alface, desfolhadas manualmente e divididas em controle, tratadas com vinagre e tratadas com cloro. Para análise parasitológica foi utilizado o método de sedimentação espontânea. Para análise estatística descritiva foi utilizado os programas Microsoft Excel l0 e para análise estatística inferencial foi utilizado o programa Bioetat 5.0 (p≤ 0,05). Todas amostras foram positivas para algum tipo de parasitose em diferentes estágios e graus parasitários. Das 27 amostras, 85,71% apresentavam parasitas, 67,85% com organismos potencialmente parasitas e em 100% deles apresentavam organismos de vida livre. Os vegetais com maior grau parasitário foram os da feira, com 36,95% de organismos parasitas. Em relação aos tratamentos utilizados, no vinagre foi encontrado um maior número de parasitas, sugerindo que mais organismos se desprenderam da verdura, tornando-a mais adequada ao consumo.

Evaluation of plant extracts for the management of Cercospora leaf spot of groundnut (Arachis hypogaea L.)

Groundnut (Arachis hypogaea L.) is a leguminous crop with high economic and nutritional value. However, increased production is hampered by Cercospora leaf spot (CLS) caused by Cercospora arachidicola and Cercosporidium personatum. Studies were conducted in vitro and in vivo to evaluate the efficacy of aqueous extracts of desert date seed (DDSE), neem seed (NSE), jatropha seed (JSE) and tobacco leaf (TLE) for the management of CLS. The antifungal activities of 25, 50, 75 and 100 g/l concentrations of each of the plant extracts was assessed in vitro on potato dextrose agar using the food poison technique. The field study was a factorial experiment consisting of 18 treatments laid in a Randomised Complete Block Design with four replications over two cropping seasons. The in vitro results revealed that all the botanicals at 100 g/l recorded the highest inhibition percentages. DDSE at 100 g/l significantly (P < 0.001) inhibited the highest mycelia growths compared to other levels of plant extracts used with inhibition percentages of 90.33 and 84.96% in C. arachidicola and C. personatum, respectively. Three out of the four aqueous extracts (DDSE, NSE and JSE) at 100 g/l significantly (P < 0.05) lowered disease incidence, severity and defoliation in the field and increased yield. Pod yield was significantly (P < 0.05) higher in plants treated with JSE, NSE, DDSE and Topsin-M, compared to those treated with TLE and the negative control plants. For most of the parameters, DDSE produced similar results as Topsin-M followed by NSE and JSE. Farmers can adopt DDSE, NSE and JSE as alternatives to fungicides leading to minimal effect on the environment since they are biodegradable. Key words: Cercospora leaf spot, plant extracts, groundnut, incidence, severity, aqueous.

Melhoria da qualidade da uva ‘Primitivo’ por desfolha manual e aplicação de ácido abscísico

As condições climáticas têm uma forte influência no cultivo da videira. A alta precipitação e as baixas temperaturas, por exemplo, podem fazer com que as uvas não atinjam índices de maturação adequados. Com o objetivo de verificar o efeito da desfolha e da aplicação de ácido abscísico (S-ABA) na melhoria da qualidade da uva, foi realizado um experimento em um vinhedo comercial da uva ‘Primitivo’, no Sul do Brasil, durante duas safras. Os tratamentos foram os seguintes: 1) controle; 2) desfolha manual no início da maturação ('veraison'); 3) 15 dias após a primeira desfolha manual; 4) ácido abscísico 200 mg L-1; 5) ácido abscísico 400 mg L-1; 6) ácido abscísico 600 mg L-1. Foram avaliadas as variáveis ​​sólidos solúveis, acidez titulável, polifenóis totais e antocianinas, intensidade de cor nas bagas, radiação fotossinteticamente ativa, índice de clorofila, porcentagem de desfolha e clorose. A desfolha manual realizada 15 dias após a primeira desfolha aumentou os sólidos solúveis e reduziu a acidez titulável, enquanto a aplicação de 400 mg L-1 de S-ABA aumentou a acidez titulável do mosto de uva. Houve uma maior radiação fotossinteticamente ativa próximo ao cacho para tratamentos de desfolha e S-ABA. A aplicação de S-ABA proporcionou clorose nas folhas, seguida de baixo teor de clorofila, causando a senescência. Portanto, a desfolha 15 dias após a primeira desfolha manual influenciou os sólidos solúveis e a acidez titulável, e a aplicação de ácido abscísico aumentou os níveis de polifenóis totais, antocianinas e a intensidade da cor nas cascas das bagas ‘Primitivo’.

Dispersal of the Zoophytophagous Predator Brontocoris tabidus and Podisus nigrispinus (Heteroptera: Pentatomidae) in an Eucalyptus Plantation

Forest plantations, especially eucalyptus, increase wood supply, avoid deforestation of native plants, and preserve local biodiversity. Defoliating caterpillars often reduce the productivity of these plantations. Rearing and releasing pentatomid predators is a strategy to manage these pests biologically. In this study, the predators Brontocoris tabidus (Signoret) and Podisus nigrispinus (Dallas) (both Heteroptera: Pentatomidae) were evaluated in a clonal eucalyptus (Eucalyptus urophylla Blake × Eucalyptus grandis W. Hill ex Maiden) (both Myrtaceae) plantation. Brontocoris tabidus dispersed further than P. nigrispinus over the 7-d trial. Males of both species dispersed more than females, and most P. nigrispinus were found within 10 m from the release point, whereas the majority of B. tabidus were observed between 15 and 30 m from their initial position of release. Resumo Plantios florestal, especialmente de eucalipto, garante o fornecimento madeira, evitando o desmatamento de florestas nativas e preserva a biodiversidade local. As lagartas desfolhadoras frequentemente reduzem a produtividade dessas plantacoes. A criacao e liberacao de pentatomideos predadores e uma estrategia para manejar essas pragas, biologicamente. Nesse estudo, os predadores Brontocoris tabidus (Signoret) e Podisus nigrispinus (Dallas) e (Heteroptera: Pentatomidae) foram avaliados em plantio clonal de eucalipto (Eucalyptus urophylla Blake × Eucalyptus grandis W. Hill ex Maiden) (Myrtaceae). Brontocoris tabidus dispersou mais que P. nigrispinus ao longo de sete dias de avaliacao. Machos de ambas as especies se dispersaram mais que as femeas, e a maioria dos individuos de P. nigrispinus foram localizados a 10 metros do ponto de liberacao enquanto a maioria de B. tabidus foram observados entre 15 a 30 metros da posicao inicial em que foram liberados. Key Words: distance traveled; longer coverage; lower density; releasing technique View this article in BioOne

Increase Of Death Malady And Energy Situation Of Trees Of Choosy Aspect During A Frequently Contribute Fagus Beam-Point Stance

We tend to compare the results of observations of bark death malady and defoliation of Fagus absorptive organs administrated in 1998 and 2002. A frequently managed, 53-year previous Fagus beam -point interchange Central European country was chosen as Associate in Nursing object of our analysis. it had been found that death malady had Associate in Nursing increasing trend. The degree of death malady indicated on trees of choosy aspect that area unit the most focus of interest of silvicultural managers was not up to the degree of death malady on the opposite trees within the same stance layer (trees of undiscriminating quality). The defoliation of absorptive organs wasn't influenced by Associate in Nursing increasing trend of death malady increase . it had been confirmed that the strategy of crown thinnings realized with the aim to support the trees of choosy quality, combined with healthful choice, was affordable conjointly in Fagus beam -point stances suffering from gangrene. throughout the analysis amount within the studied stance we tend to detected four tracheomycotic fungi of Nectria (Fr.) Fr. genus and 2 species of imperfect fungi of the genus Cylindrocarpon Wollenw. and fungus Nees.

Defoliation and Fruit Coloration in ‘Fuji’/M.9 Apple Affected by Cu-EDTA and Fe-EDTA Foliar Spray

Defoliation and Fruit Coloration in ‘Fuji’/M.9 Apple Affected by Cu-EDTA and Fe-EDTA Foliar Spray

Severity of rust (Olivea tectonae) in different clones of teak in northern Mato Grosso

The fungus Olivea tectonae , has been increasing attention from different countries of course have teak or commercial plantations with the species, as it causes severe defoliation of plants, contributing to the reduction of production. The objective was to monitor different teak clones, with five months in Sinop / MT, with respect to the fungus O. tectonae , causal agent of rust. The study of disease progress was made between the months of May 2009 to July 2010, evaluating the severity visually in three regions of the plant: upper, middle and lower. We analyzed ten different clones C1, C2, C3, C4, C5, C6, C7, C8, C9, C10 and, after completion of data collection built up the area under the disease progress curve (AUDPC). The results showed that clone C7 was most likely at the top (AAPCD 35,45) and clone C1 was the most resistant (AACPD 22,37). The C9, C8 and C10 clones are statistically equal, more likely in the middle region (AAPCD 6.332,02; 5.873,34; 5.759,75, respectively) and C5 more resistant clone in this region (AACPD 1.872,70). In the lower region the clone C5 was the toughest (AACPD 5.691,06) and the C9 clone was the most likely (AACPD 15.746,73). In the analysis of the entire plant, the clone C5 was tougher (AACPD 27.603.889,00) and C9 clones C8 and C10 were statistically equal, proving to be the most susceptible to rust (AACPD 78.872.378,00; 68.335.115,00 e 65.686.893,00 respectively).

A qPCR-based method for detection and quantification of Polystigma amygdalinum , the cause of red leaf blotch of almond

Red leaf blotch of almond, caused by the fungus Polystigma amygdalinum , results in early defoliation of trees and decreases fruit production in many Mediterranean and Middle Eastern countries. A latent period of 30–40 d has been reported for this pathogen before disease symptoms are expressed, which makes targeted fungicide control difficult. A quantitative real-time PCR detection method was developed to detect and quantify the fungus in biological samples, to assist early detection. A primer pair was designed based on the ITS region of the fungal rDNA, and this was highly specific and sensitive, enabling detection of a minimum of 12 pg of P. amygdalinum DNA and seven ascospores in artificially-prepared ascospore suspensions. A protocol was also developed to quantify ascospores on plastic tapes which are commonly used in volumetric air samplers. The detection limit for these samples was the same as for ascospore quantification in aqueous suspensions. The pathogen was also quantified in naturally infected leaves showing different stages of disease development, including early stages of leaf infection with doubtful visual identifications. Future practical applications of the method developed here are discussed in view of improving the management of red leaf blotch of almond.

Effect of a two-year defoliation episode on the photosynthesis and growth of Pinus radiata : does the lower half canopy matter?

Effect of a two-year defoliation episode on the photosynthesis and growth of Pinus radiata : does the lower half canopy matter?

Examination of biogenic amines in grapevine musts originating from vineyards treated with different viticultural practices

ABSTRACTViticultural practices as defoliation (DF) and cluster tipping (CT) (hereinafter referred to as the abbreviation) are often used for crop regulation to enhance quality. Reduced yield can be accompanied not only with more favourable sugar-acid composition but also with changes of other chemical compounds in the berries, for example, biogenic amines as well. The latter play a significant role in human health. The experiment has been carried out at three different growing sites of Hungary in 2014. DF was done at full bloom, CT occurred when the berry reached pea size. Berry sampling for biogenic amine analysis was carried out several times during the ripening period. In our trial, we examined the effect of the above-mentioned treatments, the sites and the sampling dates on the amount of berries’ biogenic amine content. We concluded that DF and CT changed the amount of each type of amines in the berries. According to our measurements the treatments and the site did affect the amount and composition of biogenic amines, but the sampling time not. The treatments were most effective in the case of histamine which is crucial for triggering allergic reactions.

Dendroindication of Retrospective Larch Defoliation

Dendroindication of Retrospective Larch Defoliation

ISOLATION, IDENTIFICATION AND PATHOGENICITY OF BOTRYOSPHAERIACEAE AND PHAEOACREMONIUM SPECIES ASSOCIATED WITH DECLINE OF PRUNUS SPECIES IN IRAN

Between 2011 and 2013, a field survey was undertaken on stone fruit trees in four provinces of Iran to determine the fungal trunk pathogens associated with decline diseases. Wood samples were collected from branches of apricot, peach, cherry, sour cherry and greengage trees showing yellowing, dieback, defoliation, canker, gummosis, decline and internal wood discolouration. Five Phaeoacremonium species, including Phaeoacremonium minimum, P. parasiticum, P. viticola, P. tuscanum and P. krajdenii and six species of Botryosphaeriaceae, namely Diplodia seriata, D. mutila, Neofusicoccum parvum, Botryosphaeria dothidea, Spencermartinsia viticola and Lasiodiplodia theobromae, were isolated and identified based on morphology, culture characteristics and DNA sequence analyses. Pathogenicity tests of candidate fungi were conducted by artificially inoculating detached shoots of all host species with a pathogen-colonized agar plug then covered with Parafilm. 30 days post inoculation, the length of the necrotic wood lesions was measured. Neofusicoccum parvum was the most virulent among the six Botryosphaeriaceae species tested. Of Phaeoacremonium species, P. parasiticum produced the longest necrotic lesions on all inoculated hosts. The following are first reports from this study: (i) P. tuscanum on peach trees; (ii) L. theobromae, B. dothidea, and P. krajdenii on apricot trees; (iii) B. dothidea, S. viticola, D. seriata, D. mutila, P. parasiticum, P. viticola and P. minimum on cherry; (iv) D. seriata, P. minimum and P. parasiticum on sour cherry and (v) S. viticola, L. theobromae and D. seriata on greengage. Phaeoacremonium krajdenii has not yet been reported from Iran and the present study is the first report of this species in this country.

Sequential sampling for evaluation of caterpillars, small and large in soybean

Among the main limitations of grain yield in soybean are the insect pests, especially the defoliating caterpillars. It is necessary to reveal and quantify these insects for proper decision-making according to pre-established control levels. So, for the implementation of appropriate management of these soybean insect pests, there is a necessity to establish a sampling plan that will allow an effective, reliable and less time consuming estimation of the population density of pests. This work aims to establish a sequential sampling plan for small and large caterpillars in soybean in accordance with the sequential test of probability rates. Data was collected for two growing seasons (2010/2011 and 2012/2013). The number of small caterpillars ( 1.5 cm) of the species Anticarsia gemmatalis (Hubner, 1818), Chrysodeixis includens (Walker, 1857) and Spodoptera eridania (Cramer, 1872) was estimated using the vertical cloth-to-beat in a grid of 154 sample points marked with a 20 × 20 m spacing in an area of 6.16 ha of soybean. The distribution of small and large caterpillars in soybean is aggregated. According to the sequential sampling plan, the number of maximum samples, for the decision making of the control or not of caterpillars in soybean is 30 samples units. Key words: Pest management, sampling plan, vertical cloth-to-beat, spatial distribution.

FIRST REPORT OF FUSARIUM WILT OF ALBIZIA JULIBRISSIN CAUSED BY FUSARIUM OXYSPORUM f. sp. PERNICIOSUM IN SPAIN

In 2014, Albizia julibrissin trees located in gardens at Logrono municipality (La Rioja, Northern Spain) showed wilt symptoms, including defoliation, internal black streaks and, finally, tree death. Necrotic wood samples were surface disinfected for 1 min in 1.5% NaOCl, washed twice with sterile distilled water, plated onto potato dextrose agar (PDA) amended with streptomycin sulfate (0.5 g l–1), and incubated at 25°C in the dark. Fusarium colonies were consistently isolated and transferred to Spezieller Nahrstoffarmer agar (SNA). Ten days after incubation at 25oC, all isolates were identified as F. oxysporum, based on the presence of short monophialides, abundant microconidia produced in false heads (length 7.5 to 12.5 μm, average 9.20 μm) and chlamydospores, and sparse, usually three-septate, macroconidia (length 21.25 to 40 μm, average 29.70 μm) (Leslie and Summerell, 2006). The translation elongation factor 1-alpha gene (TEF) region of the isolates was amplified with primers EF1 and EF2 (O’Donnell et al., 1998). Sequences showed 99% identity with a sequence of F. oxysporum f. sp. perniciosum (FJ985413). One sequence was deposited into GenBank (accession No. KU050689). Pathogenicity of isolates GIHF-019 and GIHF-021, was determined on one-year-old A. julibrissin plants grown in sterile peat moss, which were inoculated by watering the roots with 100 ml of a conidial suspension (106 conidia ml–1). Plants were maintained at 25oC in a growth chamber under a photoperiod of 12 h. Two months after inoculation all inoculated plants wilted and the fungus was reisolated from them. To our knowledge, this is the first report of F. oxysporum f. sp. perniciosum in Spain.

FIRST REPORT OF POWDERY MILDEW, CAUSED BY ARTHROCLADIELLA MOUGEOTII, ON GOJI BERRY IN TURKEY

Lycium barbarum, known as Goji berry or wolfberry, is a Chinese medicine plant in the family Solanaceae, and has been recently cultivated in Bolu, Turkey. During autumn 2015, severe powdery mildew symptoms were observed on Goji berry plantation area. White to grayish white fungal mycelia were shown on leaves and stems. Also, brownish discolorations and defoliation were exhibited. Microscope examination showed that conidia were formed in chains, hyaline, short-cylindrical and their length and width ranged from 19 to 31 (mean=26.2) μm and from 10 to 14.5 (mean=13.2) μm, respectively. Apothecial structures were not observed. The fungus was identified as Arthrocladiella mougeotii on the basis of morphological characteristics and the host specialization (Braun, 1987). To verify the identification, DNA isolation was performed by using the conidia collected by scraping from surface of infected leaves. The rDNA internal transcribed spacer (ITS) region including 5.8S rDNA was amplified using primers ITS5 (White et al., 1990) and p3 (Kusaba and Tsuge, 1995) and sequenced. The amplified 640 bp product (GenBank accession No. KX017568) revealed 99% genetic similarity with the sequences of an A. mougeotii isolate previously reported (AB022380). Pathogenicity was performed by gently pressing diseased leaves onto young leaves of one-year-old healthy plants. Non-inoculated Goji berry plants were used as control. All plants were transferred to a greenhouse. A month later, the fungus having identical morphological features was observed only on infected plants. To the best of our knowledge, this is the first report of A. mougeotii on Goji berry in Turkey.

Optimization and test for spraying parameters of cotton defoliant sprayer

Boom sprayer is widely used in large farm crops because of its high working efficiency and favorable spraying effect. But there are still some problems in cotton defoliant spraying in Xinjiang, China. Cotton is planted in a high density in Xinjiang, the row space is 10+66 cm, leaves in two adjacent rows are seriously overlapped, the lower leavers are poorly sprayed, so the defoliation effect is poor, and the cotton quality is degraded. To solve this problem and improve the defoliant droplets coverage on the cotton canopy, the original boom spraying was modified, and the spraying pardameters was optimized by the central combination test and design concept of Box-Behnken based on a single-factor test. A quadratic polynomial model of droplets coverage was created by using working parameters including horizontal spraying boom height, hang boom height and nozzles angle as the influential factors and the mean droplets coverage on cotton canopy as the target function, and the effectiveness of mode and interaction of factors were analyzed. The model was optimized and analyzed using the regression analysis method and response surface analysis method of software Design-Expert 7.0.0, and the optimal combination of spraying parameters was obtained. The results showed that the droplets coverage on cotton canopy were influenced by boom height, sprayer height and angled nozzles sequentially from large to small, and the optimal combination of spraying parameters was under horizontal spraying boom height of 134 cm, hang spraying boom height of 27.5 cm and nozzles angle of 21°. The mean droplets coverage of experimental value and predicted value on cotton canopy were 19.6% and 20.43% respectively in such conditions, and the relative error to the estimated value on the model was –4.25%. The research result can provide a reference for further optimizing the spraying parameters of cotton defoliant sprayer. Keywords: pesticide sprayer, cotton, spraying parameter, optimization, mathematical model, response surface DOI: 10.3965/j.ijabe.20160904.2125 Citation: Qin W C, Xue X Y, Cui L F, Zhou Q Q, Xu Z F, Chang F L. Optimization and test for spraying parameters of cotton defoliant sprayer. Int J Agric & Biol Eng, 2016; 9(4): 63－72.