Efficacy of curative applications of submicron chitosan dispersions on anthracnose intensity and vegetative growth of dragon fruit plants

The antifungal potential of submicron chitosan dispersions (SCD) and its effect on the vegetative growth of dragon fruit plants were studied under field conditions. There was a reduction in disease incidence (15.65%) with a severity score of 1.60 in plants treated with SCD of 600 nm droplet size of 1.0% chitosan compared to the control plants. Moreover, a significant increase was also observed among the treatments in terms of number of shoots per cutting, stem diameter and shoot length. However, the highest number of shoots (19), maximum stem diameter (0.23 m) and maximum stem length (2.80 m) were observed in plants treated with SCD of 600 nm droplet size of 1.0% chitosan. Similarly, chlorophyll content were also high in plants receiving SCD of 600 nm droplet size of 1.0% chitosan. Therefore, it can be concluded from the results that, instead of applying chitosan in the conventional form, it can be more effective as an antifungal agent as well as plant growth enhancer when applied in the form of submicron dispersions.     

Effects of fruit dipping in hydrochloric acid then rinsing in water on fruit decay and browning of longan fruit

The objective of this study was to find alternative methods for the control of pericarp browning in longan fruits (Dimocarpus longan Lour.) cv. Daw in order to replace the use of sulfur dioxide (SO₂). Experiments were conducted by dipping fruits in 1.5 N HCl solution (pH 0.21) for 20 min followed by draining. The effects of subsequent rinsing in water were also investigated. Untreated fruits and SO₂ fumigated fruits were used as controls. Fruits from each treatment were then packaged in commercial perforated plastic baskets and stored at 3 ± 1 °C, 85% RH for 60 days. It was found that dipping the fruits in HCl controlled disease development compared with the untreated fruits. In addition, dipping the fruits in HCl as well as fumigating with SO₂ gave the best control of pericarp browning. After 5 days, the pericarp of untreated fruits became brown. Dipping fruits in HCl without rinsing reduced pericarp and juice pH and increased titratable acidity which lowered eating quality. Sensory analysis was carried out to determine aril color as well as appearance, firmness, flavor and taste. Dipping in 1.5 N HCl for 20 min and rinsing exhibited higher efficacy than dipping for 0, 10 or 15 min in controlling fruit decay and maintaining fruit color and eating qualities during 7 days storage at 25 °C following 45 days storage at 5 ± 1 °C. Therefore, dipping in 1.5 N HCl for 20 min, followed by rinsing in water can be considered for commercial application in extending shelf life, decreasing fruit decay and maintaining fruit quality of longan fruits.     

氯化钙对花生中黄曲霉毒素B1提取及其快速检测结果的影响

本文以氯化钙为蛋白沉淀剂、黄曲霉毒素B1为靶标,探究了70%甲醇水（V/V）提取液中不同含量氯化钙对花生中黄曲霉毒素提取及其免疫检测结果的影响;采用样品加标回收的方法,研究比较了五种不同含量氯化钙对胶体金免疫层析试纸条和ELISA检测结果的影响。研究结果表明,样品经含1% CaCl2 （m/V）的甲醇水处理后,用胶体金免疫层析试纸条检测时,试纸条T线颜色梯度变化,不同浓度加标回收率等参数均得到明显改善,前处理效果显著;选取20份花生实际样品,经过这种前处理之后,进行胶体金免疫层析试纸条和ELISA检测,同时将其检测结果与免疫亲和层析高效液相色谱法（IAC-HPLC）进行比对,胶体金免疫层析试纸条与IAC-HPLC检测结果符合率为90%,间接竞争ELISA与IAC-HPLC检测结果相关性系数达0.996,表明本研究所改进的样品前处理方法能提高免疫检测准确度,具有很好的应用性。     

Use of netting and whitewash spray to protect papaya plants against Nivun Haamir (NH)-dieback disease

A disease causing the decline of papaya (Carica papaya) plants was noticed in the Jordan Valley in 1982. The disease caused severe yellowing of the upper leaves and dieback of the apex. The disease was not transmissible mechanically and continued efforts to associate viruses and viroids have so far been unsuccessful. Epidemiological observations suggested that the disease is airborne and probably caused by a mollicute. In order to test this hypothesis, plots were covered by an insect-proof net and with white nets providing 15, 30 and 50% shade. The 30%, 50% and insect-proof nettings provided complete protection, and the 15% netting reduced disease incidence to <2%, compared with>37% in the uncovered control plot. Spraying plants at weekly intervals with a commercial whitewash solution was also found to be effective in reducing disease incidence. The advantages of using a range of netting field treatments as a simple means for obtaining information on the epidemiological nature of a new disease are described.     

Effect of cereal-legumechapati diets on absorption and retention of calcium

Wheatchapati, wheat+Bengal gram (8020 and 7030)chapatis and casein diets, at 10 percent protein level, were fed to rats for 12 weeks to study the effect on calcium utilization. The supplementation of Bengal gram to wheat diets significantly improved the calcium absorption. The urinary calcium excretion in wheat+Bengal gramchapati diets was significantly less than that of wheatchapati diet fed group. The in vivo⁴⁵Ca absorption (CPM/100 l serum) was also less in wheatchapati group as compared to wheat+Bengal gramchapati diets fed groups. The supplementation of legumes to cereals improved the calcium utilization and it may be concluded that there will be no risk of occurance of protein induced hypercalciuria.     

Effect of watered-in demethylation-inhibitor fungicide and paclobutrazol applications on foliar disease severity and turfgrass quality of creeping bentgrass putting greens

Preventive, watered-in applications of DMI fungicides provide control of several soilborne turfgrass diseases on golf putting greens. The objectives of this two-year field study were to determine the impact of these applications on foliar diseases, and evaluate the impact of application timing of paclobutrazol, a plant growth regulator, on disease severity and turfgrass quality. Triadimefon (1.58 kg a.i. ha⁻¹), tebuconazole (0.82 kg a.i. ha⁻¹), metconazole (0.43 kg a.i. ha⁻¹), and triticonazole (0.64 kg a.i. ha⁻¹), were applied twice in late April and May and immediately watered in to the soil profile with 5 mm of post application irrigation. Paclobutrazol (0.28 kg a.i. ha⁻¹) was applied alone, in a tank-mix with the fungicide application, 7 days or 14 days after the fungicide application. Overall dollar spot severity, assessed as area under the disease progress curve (AUDPC), was significantly lower in fungicide treated plots than non-treated plots in both trial years. The date of threshold symptom observation (≥5 infection centers per plot), however, was not different between fungicide treated and non-treated plots in 2011. Triadimefon treated plots had lower AUDPC values than other fungicide treatments. Brown patch severity was not significantly different among treatments. Paclobutrazol applied alone did not reduce dollar spot or brown patch severity, however, paclobutrazol + fungicide treatments resulted in lower dollar spot severity than plots treated with fungicide alone. Short-lived phytotoxicity (bronze discoloration) was observed in plots treated with triadimefon or paclobutrazol + fungicide. Spring preventive fungicide applications targeted at soilborne disease control also provided residual control of dollar spot in this study.     

钙对花生植株生长和叶片活性氧防御系统的影响

水培条件下设置不同钙离子施用量,研究了施钙对花生泉花10号生长发育和叶片活性氧防御系统的影响.结果表明,高钙处理的植株高大,茎枝粗壮,叶片厚且大,果量多,果大饱满,叶片叶绿素含量、过氧化氢酶(CAT)活性、过氧化物酶(POD)活性较高,脂质过氧化产物丙二醛(MDA)含量、O2-·产生速率、电导率值较低.低钙对花生生长发育的影响与植株体内活性氧防御系统受到破坏密切相关.     

Effect of biocontrol agent Bacillus amyloliquefaciens and 1-methyl cyclopropene on the control of postharvest diseases and maintenance of fruit quality

Efficacy of biocontrol agent Bacillus amyloliquefaciens PPCB004 was evaluated on the control of anthracnose and phomopsis rot in ‘Solo’ papaya pre-treated with 1-methyl cyclopropene (100 μl) (1-MCP) during storage. This treatment was compared to the untreated control, commercial treatment (washing in chlorinated water), stand alone 1-MCP and PPCB004 treatment. Although fruit pre-treated with 1-MCP delayed the ripening (100% yellow) after cold storage by 9-10 d, it showed higher incidence and severity of anthracnose and phomopsis rot than the fruit subjected to commercial treatment. Application of PPCB004 after 1-MCP pre-treatment (1-MCP + PPCB004) reduced the anthracnose and phomopsis incidence and severity after cold storage (10 °C, 85% RH for 14 d) and ripening at 25 °C. The 1-MCP + PPCB004 treatment helped to retain the fruit firmness, overall quality and uniform yellow skin (100%) and flesh colour after ripening. The PPCB004 was effectively recovered from stand alone PPCB004 and 1-MCP + PPCB004 treated fruit after cold storage and ripening. The PPCB004 population showed an increase by 1 log units after ripening in 1-MCP + PPCB004 treated fruit. After ripening the recovery of PPCB004 population was higher (0.7 log units) in 1-MCP + PPCB004. The total recovery of fungal population on the fruit surface after ripening was lower in 1-MCP + PPCB004 and stand alone PPCB004 treated fruit. It can be concluded that application of B. amyloliquefaciens PPCB004 with 1-MCP pre-treated papaya (at 25-30% skin yellow stage) can significantly reduce disease incidence associated with 1-MCP treatment. This treatment has the potential for commercial application in the ‘organic’ papaya industry.     

常规施肥与钙肥不同加量对讷河市大豆产量的影响

通过3年7项次的大豆常规施肥与钙肥的不同加量的效果试验,研究了大豆施用钙肥的增产效果和效益。结果表明,适量增加钙肥的施用对大豆有明显的增产效果,其增产与效益表现为8kgCaO〉10kgCaO〉5ksCaO〉2kgCaO〉CK〉15kgCaO〉20kgCaO。     

甜菜碱处理对番木瓜果实采后冷害及抗氧化系统的影响

以海南主栽品种‘中白’番木瓜为试材,采用15 mmol/L甜菜碱浸泡处理,随后于冷害温度6℃下贮藏,研究甜菜碱处理对番木瓜冷害及其抗氧化代谢的影响。结果表明,甜菜碱处理可有效地抑制番木瓜果实SOD、POD和CAT酶活性的下降,使超氧阴离子产生速率和过氧化氢浓度保持较低的水平,减少细胞膜透性的增加和膜脂过氧化产物MDA的积累,减缓了番木瓜果实采后冷害的发生。     

Effect of Pichia membranaefaciens on ROS metabolism and postharvest disease control in citrus fruit

The yeast Pichia membranaefaciens has antagonistic effects against a wide range of phytopathogenic fungi that cause postharvest fruit decay. This work evaluated the effects of P. membranaefaciens on the reactive oxygen species (ROS) metabolism and disease control in harvested citrus fruit (Citrus sinensis L. Osbeck). The lesion diameter caused by Penicillium italicum and Penicillium digitatum on citrus fruit was remarkably reduced when the fruit was point-inoculated or dipped in a suspension of P. membranaefaciens at 1 × 10⁸ CFU mL⁻¹. The application of P. membranaefaciens on citrus fruit enhanced the activity of superoxide dismutase, ascorbate peroxidase, and glutathione reductase, as well as the levels of hydrogen peroxide, the superoxide anion and glutathione, but inhibited the decreasing ascorbic acid content. Furthermore, catalase activity was decreased by the same treatment. These results indicated that yeast treatment induced the synthesis of antioxidant enzymes which might have antagonistic effects against postharvest green and blue mold infection in citrus fruit.     

施用不同配比肥料对番木瓜产量与品质的影响

为探讨不同氮磷钾配合施肥对海南地区番木瓜产量和品质的影响,在海南儋州地区进行了氮磷钾不同配比施肥试验。结果表明:施肥可增加番木瓜的产量,不同氮磷钾的施肥组合有不同的增产效果,增产率变化在25.30%~69.08%之间。其中氮的增产效果最好,磷肥次之,钾肥最差。结合氮、磷、钾各水平的增产情况和经济效益分析,认为N 340 g/株、P2O5470 g/株和K2O 340 g/株为番木瓜高产的推荐配方。番木瓜不同品质指标对氮磷钾不同水平组合的响应不同。施肥显著增加单果重,增幅在5.92%~23.64%之间。钾对单果重的贡献优于磷,氮最差。尽管施肥没有造成番木瓜大多品质指标上的显著差异,但从各品质指标与各元素水平之间的变化趋势关系上给出施肥建议是,番木瓜要维持较高品质,必须慎施氮肥,多施磷、钾肥。结合经济效益和环保因素,从理论上N 210 g/株、P2O5210 g/株和K2O 340 g/株为番木瓜优质的推荐配方。     

Evaluation of electrolyzed oxidizing water for phytotoxic effects and pre-harvest management of gray mold disease on strawberry plants

Near neutral (pH = 6.3-6.5) electrolyzed oxidizing water (EO water) has been demonstrated to inactivate fungi in pure culture and to mitigate infection on fruit surfaces. One possible alternative or supplement to traditional pre-harvest crop management practices that currently rely on the use of large quantities of fungicides is near neutral EO water. In the present work, treatment of Botrytis cinerea or Monilinia fructicola with near neutral EO water (50 or 100 ppm total residual chlorine (TRC)) in pure culture resulted in a 10⁶ reduction and 100% inactivation as evidenced by negative broth enrichment. When applied in concert with 50 or 100 ppm EO water, treatments of Captan 50WP (captan), Rovral (iprodione), Iprodione 4LAG (iprodione), or Switch 62.5 WDG (cyprodinil and fludioxonil) effectively inhibited fungal growth of B. cinerea as evidenced by a 10⁶ reduction on the direct plate and negative broth enrichment. Treatments of Captan 50WG (captan), Rovral (iprodione), Iprodione 4LAG (iprodione), Switch 62.5 WDG (cyprodinil and fludioxonil), Captan 80 WDG (captan), or Captevate (captan and fenhexamide) when applied in concert with 50 or 100 ppm EO resulted in a 10⁶ reduction of M. Fructicola and 100% inactivation as evidenced by negative broth enrichment. Strawberry plants sprayed with EO water (pH = 6.3-6.5) at concentrations of 50 and 100 ppm TRC once per week, did not result in significant (P > 0.05) phytotoxicity relative to a water (0 ppm TRC) treatment. In this study, the application of 100 ppm EO water (pH = 6.3-6.5) twice per week to strawberry plants infected with B. cinerea was more effective (P ≤ 0.05) than a once per week Captan application and as effective as a once per week captan/once per week EO treatment. The once per week captan/once per week EO treatment was significantly more effective (P ≤ 0.05) than the captan once per week treatment. Dip treatments of strawberries in near neutral EO solutions (50 and 100 ppm TRC; pH = 6.3-6.5) did not leave a chlorine residue on the fruit relative to a water dip. The results from this study suggest that near neutral EO solutions could be used to manage infection of B. cinerea on strawberry plants in the field and also as a disinfection solution for harvesting equipment, greenhouses, packing houses and in commercial facilities to prevent or manage infections of B. cinerea and M. fructicola.     

Effects of Bacillus subtilis strain QST 713 and storage temperatures on post-harvest disease development on greenhouse tomatoes

Tomato plants in two commercial greenhouses were treated with Rhapsody (Bacillus subtilis strain QST 713, rate of 1.45%) once every 4 weeks during 2012–2013 to determine effects on post-harvest fruit infection. Populations of Bacillus and disease incidence were monitored weekly from harvested fruit over an 18-week period. Population levels of Bacillus ranged from 75 to 110 × 10⁴ colony forming units (cfu) cm⁻² of fruit surface area one week after application to 25–30 × 10⁴ cfu cm⁻² of fruit surface area 4 weeks after application. Disease incidence on harvested fruit incubated at 21 °C for 7–10 days was variable, due to variation in inoculum levels within the greenhouse as well as variable environmental conditions. Both disease incidence and severity were significantly reduced on Rhapsody-treated fruit, especially in the 1–2 week period following application. Post-harvest storage temperature (13 °C vs. 21 °C) and incubation time (12 vs. 16 days) had a significant effect on final disease severity. Rhapsody-treated fruit incubated at 13 °C had an average of 1–2% fruit infection compared to up to 20% infection on untreated fruit at 21 °C. The most frequent pathogens affecting fruit quality were Penicillium sp. and Rhizopus stolonifer. Rhapsody applications made every 4 weeks maintained sufficiently high populations of Bacillus on the fruit surface to prevent spread of these fungi onto the fruit, resulting in significant post-harvest disease control on fresh market tomatoes. When combined with storage at 13 °C for no more than 12 days, disease was reduced to negligible levels.     

Trunk applications of phosphite for the control of foliar and fruit scab on pecan

Pecan scab (Fusicladium effusum) is the major disease of pecan in the southeastern United States. Apart from issues of fungicide resistance and the need to test efficacy of novel fungicides such as phosphites, management of the disease in tall trees is challenging due to the technical difficulties of getting sufficient spray coverage to the upper parts of the canopy. The use of trunk application of phosphite, which is systemically transported within the tree, was investigated in six separate experiments in 2010 and 2011. Spray application of phosphite to the trunks of young 3 to 4 year-old trees provided excellent control of scab on foliage of cultivar Desirable, but slightly less control on the susceptible cultivar Wichita, but neither incidence nor severity of scab was reduced on 11 to 12 year-old trees of cultivar Desirable by trunk-spray application in 2010, although slightly less severe disease was observed in 2011. In two factorial cultivar × fungicide treatment experiments in 2010 and 2011 using 13 to 14 year-old trees there was little effect of trunk applications on scab incidence or severity on foliage or fruit. However foliar application of phosphite and a conventional fungicide both significantly reduced the incidence and severity of scab on most cultivars on both foliage and fruit, confirming previous observations of the efficacy of these foliar sprays. Different methods of trunk application, for example injections of phosphite, might prove more efficacious than surface application in older trees.     

Biological control of southern stem rot caused by Sclerotium rolfsii using Trichoderma harzianum and arbuscular mycorrhizal fungi on Jerusalem artichoke (Helianthus tuberosus L.)

Efficacy of Trichoderma harzianum and the arbuscular mycorrhizal fungus (AMF) Glomus clarum for suppression of southern stem rot caused by Sclerotium rolfsii in Jerusalem artichoke was investigated in Thailand under greenhouse conditions. Experimental factors included two Jerusalem artichoke genotypes (HEL 246 and JA 37), two levels of T. harzianum and G. clarum (inoculated and blank). The biological control agents were added to the potting medium immediately before seedlings of Jerusalem artichoke were transplanted into it; 20 days later, seedlings were inoculated with S. rolfsii by placing infested sorghum seeds at the base of the stem. The combination of cv. HEL 246 with addition of both G. clarum and T. harzianum had the lowest disease incidence (30%) and required the longest time to permanent wilt (11 days after inoculation). Inoculation of cv. JA 37 and HEL 246 with G. clarum alone gave better control of the disease than did inoculation with T. harzianum alone. The results are the first published report of biological control of S. rolfsii on Jerusalem artichoke.     

Effect of Trichoderma asperellum and arbuscular mycorrhizal fungi on cacao growth and resistance against black pod disease

Arbuscular mycorrhizal fungi (AMF) and members of the genus Trichoderma have emerged as promising groups of microbial inoculants that can induce plant growth and resistance to disease. This study aimed at investigating the potential of AMF and a strain (PR11) of Trichoderma asperellum to promote cacao growth and induce resistance against Phytophthora megakarya. Cacao seedlings were either non-inoculated, or inoculated with the saprophytic fungus T. asperellum and/or a mixture of two different mycorrhizal fungi, Gigaspora margarita and Acaulospora tuberculata. Eighteen weeks after planting, a series of morphological as well as biochemical changes, which are considered to be part of the plant defense response, were measured after a challenge inoculation of the leaves with zoospores of P. megakarya. Inoculation with AMF and T. asperellum alone was essential for the promotion of plant growth. Significant increase in plant height, root and shoot fresh weights, as well as phosphorous uptake was recorded in comparison to non-inoculated control plants. However, dual inoculation of cacao seedlings with T. asperellum and AMF did not always positively benefit the plants. Leaf inoculation showed variation among the treatments, with the lowest disease index (highest level of resistance) recorded in plants inoculated with either AMF or T. asperellum only. This came along with a high synthesis of amino acids and phenolic compounds in both healthy and infected leaves, suggesting that these metabolites are implicated in disease resistance.     

Disease risk perception and diversity of management strategies by farmers: The case of anthracnose caused by Colletotrichum gloeosporioides on water yams (Dioscorea alata) in Guadeloupe

Disease perception and adequate management practices are two essential issues faced by farmers, especially in the current context of climate change which may potentially increase disease risk. We investigated the diversity of water yam cropping systems in Guadeloupe through interviews, how producers and international yam research scientists perceived anthracnose, and how this perception correlated with farmers’ risk management strategies. We found that disease perception by farmers is very close to perception by international yam experts, as both have the same perception of the hierarchy of factors translating into disease. Three different yam production strategies coexist at a local scale, where agronomic practices and socio-economic profiles are distinct and consistent with attitude toward anthracnose risk management. Six factors were perceived as decreasing the disease: associated crop species; crop rotation; staking; weeding; crop monitoring and varietal admixture. Yam producers raising crops more intensively were risk prone, while others usually sought practices to manage disease appearance and spread. Both cumulative risk and past anthracnose epidemic experiences translated into heavier reliance on chemicals. These results have practical implications for designing best yam crop management systems and control of yam anthracnose.