Control of postharvest decay on cherry tomatoes by marine yeast Rhodosporidium paludigenum and calcium chloride

Aims: In this study, the potential of calcium chloride (CaCl₂) application to improve the efficacy of the marine antagonist Rhodosporidium paludigenum in controlling postharvest diseases of cherry tomatoes was assessed. Methods and Results: CaCl₂ alone was found not to have any direct influence on the population growth of R. paludigenum in NYDB cultures or in cherry tomato wounds. However, the combined treatments with 1 × 10⁸ cells ml^?1R. paludigenum and CaCl₂ at the concentration from 0·5 to 2% showed high activities to reduce black rot caused by Alternaria alternata in cherry tomato wounds, significantly higher than those of R. paludigenum or CaCl₂ alone. Meanwhile, 0·5% CaCl₂ in combination with 1 × 10⁸ cells ml^?1R. paludigenum greatly inhibited the natural decay of cherry tomatoes in 21 days’ storage at 25°C. Conclusions: The combination of R. paludigenum and CaCl₂ enhances the inhibition of black rot and natural decay of postharvest cherry tomatoes. The results from this study provide a new way to improve the efficiency of R. paludigenum in maintaining the quality of postharvest fruits and vegetables. Significance and Impact of the Study: The marine yeast R. paludigenum combined with CaCl₂ has greatly potential use as an alternative to chemical fungicides in inhibiting postharvest decay on cherry tomatoes.     

Antibacterial activity of herbal extracts against five plant pathogenic bacteria

The present study was designed to evaluate in vitro antibacterial activity of herbal extracts against five plant pathogenic bacteria (viz. Xanthomonas campestris, Xanthomonas axonopodis pv. punicae, Erwinia spp., Pseudomonas syringae and Xanthomonas citri). Herbal extracts of leaves and rinds of Garcinia indica, rhizomes of Curcuma aromatica, roots of Glyccyrrhiza glabra, leaves of Nyctanthes arbor-tristis and seeds of Vernonia anthelmintica were used for screening. Screening was done using agar well diffusion method. Relatively potent extracts were shortlisted from this study and were further studied to find out their minimum bactericidal concentration (MBC). From the studies, it was observed that extracts of C. aromatica, G. indica and G. glabra have shown lowest MBC values among other tested plant extracts. This study indicates the potential of these potent plant extracts in the management of diseases caused by plant pathogenic bacteria.     

Antifungal activity of herbal extracts against plant pathogenic fungi

The present study was designed to evaluate in vitro antifungal activity of herbal extracts against three plant pathogenic fungi (viz. Rhizopus stolonifer, Botrytis cinerea and Colletotrichum coccodes). Extracts of leaves and rinds of Garcinia indica, rhizomes of Curcuma aromatica, roots of Glycyrrhiza gahliae, leaves of Nyctanthes arbour-tristis and seeds of Vernonia anthelmintica were used for screening. Screening was done using poisoned food technique. Relatively potent extracts were shortlisted from this study and were further assayed to find out their minimum fungicidal concentration (MFC). From the above studies, it was observed that ethyl acetate extract of rhizomes of C. aromatica and unripe fruit rinds of G. indica have shown the lowest MFC values amongst the other tested plant extracts. This study indicates that the potential of these plant extracts in the management of diseases caused by plant pathogenic fungi.     

Extending the host range of the bioherbicidal fungus Colletotrichum gloeosporioides f. sp. aeschynomene

Spore formulations of the bioherbicidal fungus Colletotrichum gloeosporioides f. sp. aeschynomene (ATCC No. 20358) (CGA) were evaluated for control of three weed species: northern jointvetch (Aeschynomene virginica), Indian jointvetch (A. indica), and hemp sesbania (Sesbania exaltata) in greenhouse experiments. Mortality, dry weight reduction, and plant height reduction of A. virginica seedlings ranged from 98% to 100%, 15 days after inoculation with CGA in water, in an invert emulsion, or in Silwet L-77 surfactant. However, CGA in water caused no effects of these parameters on S. exaltata, and only slight effects on A. indica. A. indica and S. exaltata were also severely injured (mortality, dry weight and plant height reduction, 98–100%) by CGA in the invert emulsion or in Silwet L-77. The CGA in Silwet formulation incited severe disease development more rapidly than the invert emulsion or water formulations of CGA in all species. These results suggest that the host range of CGA can be expanded though formulation modification to enable this bioherbicide to control multiple weeds, thus making this product more economically acceptable.     

Effect of Different Physical Factors on efficacy of Thevetia Peruviana leaf extract and bio-formulations

Plant extract possess various secondary metabolites which are antifungal in nature and can be used as a safer alternative to the synthetic fungicides. As we all know that the chemical fungicides are harmful not only for humans but also for animals, other vegetation and for complete ecosystem. To overcome this problem, we have to focused on another alternative which are biologically libel and nonhazardous also. In the present study, herbal formulation was prepared in various combination ratios with Thevetia peruviana leaf extracts, cow dung and neem oil cake. The major aim of this short study is to check the stability of the said plant extracts and prepared herbal formulation on various physical factors like heat, temperature, pH, sunlight and storage etc. The extracts and herbal formulations were exposed to varying conditions of the parameters selected for a precise time period, and then observing the effect as a function of change in the crude extract activity, herbal formulation activity and change minimum inhibitory concentration of plant extract against the Alternaria solani. Control set of MIC, and extract free medium were maintained for comparison in each set of experiment against Alternaria solani. Results suggested that efficacy of leaf extracts and different formulations was not affected by wet heat up to 100 °C while slight reduction in antifungal activity of the plant extract and herbal formulations were observed with dry heat at 100 °C. In addition, slight reduction in activity of extract and herbal formulations was observed with change in pH. However antifungal activity of plant extract as well as herbal formulations, remain unaffected at alkaline pH (pH 9) and neutral pH (pH7). Storage for 6 and 12 months had no negative effect on extract and herbal formulation efficacy and the antifungal activity was observed similar to freshly prepared extract activity. The present study concluded that the plant disease or plant pathogens can be controlled by plant extract and plant based bioformulations by increasing the shelf life with some little changes in the physical parameters such as light, temperature, pH and storage.     

The shelf life and effectiveness of granular formulations of Metschnikowia pulcherrima and Pichia guilliermondii yeast isolates that control postharvest decay of citrus fruit

Our overall objectives were to prepare commercially acceptable formulations of the postharvest biological control yeasts, Metschnikowia pulcherrima and Pichia guilliermondii, which have a long storage life and to determine the effectiveness of these formulations to control postharvest green and blue moulds on citrus fruit. Yeasts, grown on a cane molasses-based medium, were combined with talc or kaolin carriers and various adjuvants and the viability of yeast in 12 formulations was determined over a 6 month period. Formulation no. 11, containing talc, sodium alginate, sucrose, and yeast extract, for both yeasts had a significantly higher viable yeast cell content over a 6 month storage period. Among the formulations, three formulations (formulations no. 5, 6, and 11) were selected for additional in vivo testing because they had higher levels of viability amongst yeast cell populations during storage and were easier to resuspend remained in suspension more easily. These formulations were tested on Satsuma mandarin and grapefruit to control green and blue moulds. Formulations no. 5, 6, and 11 for both yeasts effectively controlled green mould, while only formulation no. 11 with either yeast isolate M. pulcherrima (isolate M1/1) or P. guilliermondii (isolate P1/3) effectively controlled both blue and green moulds.     

Evaluation of different formulations of potential biocontrol yeast isolates efficacy on apple blue mold at storage condition

Post-harvest pathogens cause major losses in apple production. Biological control by using epiphytic yeasts against Penicillium expansum has been considered as an alternative method for controlling the post-harvest decays. The yeast isolates Rhodotorula mucilaginosa, Pichia guilliermondii, which showed high biocontrol efficacy against P. expansum, were selected for formulation tests. Formulation is an important step in developing a biocontrol product. The successful delivery of biocontrol agents, shelf life, stability and effectiveness in commercial conditions depend on the formulation. In the formulation, the carrier is the primary material used to allow a bioproduct to be dispersed effectively. Yeast isolates were grown in a cane molasses-based medium. Harvested yeast cells were combined with inorganic (talk, kaolin) and organic (Rice bran, wheat bran) carriers. Viability of the yeast cells in formulations stored at 4°C and 24°C was determined each month during 6 months storage. After 6 months storage to evaluate efficacy of formulations, all formulations were tested on apple to control blue mold in storage condition. High stability of antagonistic yeasts was achieved by using organic and inorganic carriers. Rice bran and wheat bran stimulated the germination of the yeasts cells during storage period. Both of the yeasts had significantly highest viable yeast cell content over 6 months in formulation containing wheat bran as a carrier. P.guillermondii in all formulations had significantly higher shelf life and was effective than R. mucilaginosa.     

Impact of Piriformospora indica on tomato growth and on interaction with fungal and viral pathogens

Piriformospora indica is a root endophytic fungus with plant-promoting properties in numerous plant species and induces resistance against root and shoot pathogens in barley, wheat, and Arabidopsis. A study over several years showed that the endophyte P. indica colonised the roots of the most consumed vegetable crop tomato. P. indica improved the growth of tomato resulting in increased biomass of leaves by up to 20%. Limitation of disease severity caused by Verticillium dahliae by more than 30% was observed on tomato plants colonised by the endophyte. Further experiments were carried out in hydroponic cultures which are commonly used for the indoor production of tomatoes in central Europe. After adaptation of inoculation techniques (inoculum density, plant stage), it was shown that P. indica influences the concentration of Pepino mosaic virus in tomato shoots. The outcome of the interaction seems to be affected by light intensity. Most importantly, the endophyte increases tomato fruit biomass in hydroponic culture concerning fresh weight (up to 100%) and dry matter content (up to 20%). Hence, P. indica represents a suitable growth promoting endophyte for tomato which can be applied in production systems of this important vegetable plant not only in soil, but also in hydroponic cultures.     

Storage and formulation of the entomopathogenicnematodes Heterorhabditis indica and H. bacteriophora

Successful control of insect pests through theapplication of entomopathogenic nematode dauerjuveniles of H. bacteriophora and H.indica can only be achieved when the nematodematerial reaches the end user in good condition.Storage and formulation techniques must provideoptimum conditions to guarantee a maximum survival andinfectivity of the nematodes. Nematode survival wastested at temperatures ranging between 5–25 °C.A maximum survival of H. indica was achieved at15 °C and the highest mortality at 5 °C.H. bacteriophora survived best at 7.5 °Cand least at 25 °C. An increase of the saltconcentration had positive effects on dauer juvenilesurvival in aqueous suspensions. Low pH between 6 and4 reduced the bacterial growth and prolonged survivalof stored dauer juveniles. Of the organic acidsascorbic, benzoic, citric and sorbic acid, onlyascorbic acid had a positive effect on H. indicasurvival. Extracts of the dried spice plants cinnamon,cloves, rosemary and oregano were tested. Enhancementof H. indica survival was recorded for cinnamonand cloves. Survival and infectivity of nematodesstored in attapulgite and bentonite clays and spongewere recorded over several weeks at different storagetemperatures. Infectivity was not influenced by thedifferent formulation materials. When stored insponge at 25 °C nematodes survived less than 1week and the formulation in clay could only prolongthis period for another week. At 5 °C thesurvival of H. bacteriophora in sponge wassuperior to that in clay, whereas H. indicasurvived less well in sponge than in clay at15 °C. Storage in aerated water at 5 °Cfor H. bacteriophora and at 15 °C for H. indica resulted in the lowest mortality. Forstorage at controlled conditions (temperature, pH andosmolarity), aerated water is superior to all othermethods tested and the addition of preservatives willincrease survival.     

Using Heading date 1 preponderant alleles from indica cultivars to breed high‐yield,high‐quality japonica rice varieties for cultivation in south China

Heading date 1 (Hd1) is an important gene for the regulation of flowering in rice, but its variation in major cultivated rice varieties, and the effect of this variation on yield and quality, remains unknown. In this study, we selected 123 major rice varieties cultivated in China from 1936 to 2009 to analyse the relationship between the Hd1 alleles and yield‐related traits. Among these varieties, 19 haplotypes were detected in Hd1, including two major haplotypes (H8 and H13) in the japonica group and three major haplotypes (H14, H15 and H16) in the indica group. Analysis of allele frequencies showed that the secondary branch number was the major aimed for Chinese indica breeding. In the five major haplotypes, SNP₃₁₆(C‐T) was the only difference between the two major japonica haplotypes, and SNP₄₉₅(C‐G) and SNP₆₁₄(G‐A) are the major SNPs in the three indica haplotypes. Association analysis showed that H16 is the most preponderant allele in modern cultivated Chinese indica varieties. Backcrossing this allele into the japonica variety Chunjiang06 improved yield without decreasing grain quality. Therefore, our analysis offers a new strategy for utilizing these preponderant alleles to improve yield and quality of japonica varieties for cultivation in the southern areas of China.     

Genetic analysis of feeding preference in two related species of Altica (Coleoptera: Chrysomelidae: Alticinae)

Abstract 1. Genetic analysis of feeding preference can make an important contribution to our understanding of the evolution of host‐plant selection in phytophagous insects. Two closely related flea beetles, Altica viridicyanea (Baly) and Altica fragariae Nakane, with separate host plants [Geranium wilfordii Maxim. and Duchesnea indica (Andrews) Focke respectively] were hybridised to analyse the inheritance mode of feeding preference. 2. Adult hybrid F₁ (A. viridicyanea female × A. fragariae male) preferred G. wilfordii to D. indica in two‐choice tests, regardless of which plant they had fed on as larvae. Adults of one backcross to A. fragariae preferred D. indica to G. wilfordii, and the two backcrosses to A. viridicyanea consumed only a very small percentage of D. indica. Adult females of F₂ showed no significant preference, whereas males of F₂ showed slight preference for G. wilfordii over D. indica. 3. Both the mean feeding preference and the segregation pattern of beetles indicate that the feeding preference of A. viridicyanea and A. fragariae for G. wilfordii and D. indica, respectively, is mainly controlled by a major dominant autosomal gene (or several genes). 4. The variance between feeding preference and oviposition preference of female F₂ indicate that the two behaviour traits of Altica species are controlled by different gene(s).     

Inhibitory effect of Tamarindus indica and Carica papaya on egg hatch larva mortality of Meloidogyne incognita

Essentially, the most effective control of plant parasitic nematodes involves the use of synthetic nematicide. However, apart from their very high cost, increased concern on the environment has necessitated a reduction in the amount of nematicides used for nematode control. In view of these, this research work was conducted to evaluate the effects of different concentrations of root extract of Tamarindus indica and Carica papaya at different concentrations S (100% concentration), “S/2” (50% concentration), “S/10” (10% concentration) and “S/100”(1% concentration) in the inhibition of egg hatch and mortality of larva of root-knot nematode, Meloidogyne incognita .The experiment was laid out in a completely randomised design and replicated four times. Combination of equal proportion of T. indica and C .papaya root extract indicated that all the concentrations inhibited egg hatch. The standard solution S of all the selected botanicals were more toxic and effective at (p ≤ 0.05) than the other concentrations. Similarly, combinations of root extracts of T. indica and C. papaya were the most effective of all the selected botanicals in the inhibition of egg hatch and larvae mortality, followed by T. indica root extracts and then C. papaya root extracts.     

In vitro morphogenetic studies on three apomictic species of Garcinia

Comparison of morphogenetic potential of three important Indian species of Garcinia??G. indica, G. cambogia and G. xanthochymus has been reported. Apomictic seeds of G. indica were found to be morphogenetically most potential followed by G. cambogia. The explants of G. xanthochymus were highly recalcitrant towards in vitro conditions and failed to induce adventitious buds on any of the media tested. High frequency direct shoot bud differentiation was induced in aseptic seed cultures of G. indica and G. cambogia on MS medium supplemented with cytokinins (BAP, kinetin or TDZ). Amongst the three cytokinins tested, TDZ (0.1?C0.5???M) was most effective for adventitious bud differentiation in both G. indica and G. cambogia, however, the proliferating buds failed to elongate. Substantial number of buds induced on BAP supplemented media elongated into shoots after subculture on elongation medium. Addition of NAA along with cytokinins in the induction medium enhanced callusing without improvement in bud induction response. The induced adventitious buds were elongated on MS basal medium containing 0.2% activated charcoal. Direct rooting was achieved in both G. indica and G. cambogia on auxin supplemented media with best response at 10???M IBA concentration in both the species. The in vitro raised plantlets showed 90% survival in the field when transferred after hardening and acclimatization.     

Application of inorganic carrier-based formulations of fluorescent pseudomonads and Piriformospora indica on tomato plants and evaluation of their efficacy

Aims: Fluorescent pseudomonads are widely used as bioinoculants for improving plant growth and controlling phytopathogenic fungi. Piriformospora indica (Pi), a symbiotic root endophyte, also has beneficial effects on a number of plants. The present study focuses on the improvement of growth yields of tomato plants and control of Fusarium wilt using inorganic carrier‐based formulations of two fluorescent pseudomonad strains (R62 and R81) and Pi. Methods and Results: The inorganic carrier‐based formulations of pseudomonad strains and Pi were tested for plant growth promotion of tomato plants under glass house and field conditions. In controlled glass house experiments, 8·8‐fold increase in dry root weight and 8·6‐fold increase in dry shoot weight were observed with talcum powder‐based consortium formulation of R81 and Pi. Field trial experiments ascertained the glfass house results with a considerable amount of increase in plant growth responses, and amongst all the treatments, R81 + Pi treatment performed consistently well in field conditions with an increase of 2·6‐, 3·1‐ and 3·9‐fold increase in dry root weight, shoot weight and fruit yield, respectively. The fluorescent pseudomonad R81 and Pi also acted as biocontrol agents, as their treatments could control the incidence of wilt disease caused by Fusarium oxysporum f.sp. lycopersici in tomato plants under glass house conditions. Conclusions: The culture broths of pseudomonads R62, R81 and Pi were successfully used for development of talcum‐ and vermiculite‐based bioinoculant formulations. In controlled glasshouse experiments, the talcum‐based bioinoculant formulations performed significantly better over vermiculite‐based formulations. In field experiments the talcum‐based consortium formulation of pseudomonad R81 and Pi was most effective. Significance and Impact of the Study: This study suggests that the formulations of pseudomonad strains (R62 and R81) and Pi can be used as bioinoculants for improving the productivity of tomato plants. The application of such formulations is a step forward towards sustainable agriculture.     

Poloxamer 407-based intranasal thermoreversible gel of zolmitriptan-loaded nanoethosomes: formulation,optimization, evaluation and permeation studies

Zolmitriptan is the drug of choice for migraine, but low oral bioavailability (<50%) and recurrence of migraine lead to frequent dosing and increase in associated side effects. Increase in the residence time of drug at the site of drug absorption along with direct nose to brain targeting of zolmitriptan can be a solution to the existing problems. Hence, in the present investigation, thermoreversible intranasal gel of zolmitriptan-loaded nanoethosomes was formulated by using mucoadhesive polymers to increase the residence of the drug into the nasal cavity. The preparation of ethosomes was optimized by using 3² factorial design for percent drug entrapment efficiency, vesicle size, zeta potential, and polydispersity index. Optimized formulation E6 showed the vesicle size (171.67?nm) and entrapment efficiency (66%) when compared with the other formulations. Thermoreversible gels prepared by using poloxamer 407 showed the phase transition temperature at 32–33?°C which was in line with the nasal physiological temperature. The optimized ethosomes were loaded into the thermoreversible mucoadhesive gel optimized by varying concentrations of poloxamer 407, carbopol 934, HPMC K100, and evaluated for gel strength, gelation temperature, mucoadhesive strength, in vitro drug release, and ex vivo drug permeation, where G3 and G6 were found to be optimized formulations. In vitro drug release was studied by different kinetic models suggested that G3 (n?=?0.582) and G6 (n?=?0.648) showed Korsemeyer–Peppas (K_KP) model indicating non-Fickian release profiles. A permeation coefficient of 5.92 and 5.9?µg/cm² for G3 and G6, respectively, revealed very little difference in release rate after 24?h between both the formulations. Non-toxic nature of the gels on columnar epithelial cells was confirmed by histopathological evaluation.     

Microbial population profiles of the microflora associated with pre- and postharvest tomatoes contaminated with Salmonella typhimurium or Salmonella montevideo

Aims:  To determine the microflora profiles of pre- and postharvest tomatoes contaminated with Salmonella montevideo or S. typhimurium DT104.
Methods and Results:  Salmonella montevideo or S. typhimurium was inoculated onto the flowers of tomato plants with the microflora of the subsequent fruit examined using a combination of Source Carbon Utilization and 16S rDNA-PCR profiling. From 16S rDNA profiles it was evident that tomatoes derived from Salmonella inoculated plants harboured a different microbial population compared to nontreated controls. The same result was observed for tomatoes inoculated at postharvest and subsequently stored for 14 days at 15°C. From sequencing analysis it was found that tomatoes derived from Salmonella inoculated plants but testing negative for the enteric pathogen, frequently harboured Enterobacter and Bacillus spp. In contrast, both bacterial types were not found associated with tomatoes testing positive for Salmonella.
Conclusions:  Salmonella introduced onto tomatoes at pre- or postharvest alters the composition of the microbial community. The presence of Enterobacter and Bacillus spp negatively affects the persistence of Salmonella on preharvest tomatoes.
Significance and Impact of the Study:  Salmonella appears to modify rather than become integrated into the microbial communities associated with tomatoes. Yet, the presence of antagonistic bacteria appears to reduce the persistence of the enteric pathogen.     

Development of Pusa 5SD for seed dressing and Pusa Biopellet 10G for soil application formulations of Trichoderma harzianum and their evaluation for integrated management of dry root rot of mungbean (Vigna radiata)

Various seed dressing and soil application formulations were developed from Trichoderma viride, T. virens and T. harzianum to increase the shelf life of bio-formulations used to manage dry root rot (Rhizoctonia bataticola) of mungbean (Vigna radiata), a major yield limiting factor in mungbean production. The shelf life of the formulations developed in the present study was monitored by counting colony forming units (cfu) up to 25 months of storage at room temperature (26 ± 8 °C). A newly developed seed dressing formulation, Pusa 5SD based on peat powder (47.5%), Sabudana powder (Manihot esculenta) (47.5%) and carboxymethyl cellulose (5%) and a newly developed soil application formulation, Pusa Biopellet (PBP) based on sodium alginate, aluminium silicate, Sabudana powder and tap water (1:5:5:100 w/w/w/v) exhibited longer shelf life. Another formulation Pusa Biogranule (PBG) based on wheat and pulse brans varied in cfu counts during different periods of storage. Pusa 5SD could be used up to 25 months of storage while PBP 10G and PBG 5 could be used up to 15 months of storage (>10⁵ cfu). The efficacy of the formulations was evaluated in pot experiments against the disease. In these experiments, T. harzianum based PBP 10G and PBG 5 for soil application, and Pusa 5SD for seed treatment were found to be superior to others in reducing the dry root rot incidence, and increasing the seed germination and shoot and root lengths. However, a combination of soil application of PBP 10G (T. harzianum) and seed treatment with T. harzianum based Pusa 5SD + carboxin was found superior to the use of any of these formulations alone in reducing the dry root rot incidence (87.2%) and increasing the seed germination (43.0%), shoot length (40.3%), root length (37.0%) and grain yield (54.6%) of mungbean crop over those of untreated control under sick field conditions.     

Efficacy of salicylic acid in modulating physiological andbiochemical mechanisms to improve postharvest longevity in cut spikes of Consolida ajacis (L.) Schur.

Postharvest losses of cut flowers is one of the considerable challenges restricting their efficient marketability. Consequently, such challenges have triggered a constant hunt for developing compatible postharvest treatments to mitigate postharvest losses. Interestingly, recent studies entrench extensive role of salicylic acid (SA) in mitigating postharvest losses in various flower systems. The current investigation focusses on role of SA in augmenting physiological and biochemical responses to mitigate postharvest senescence in cut spikes of Consolida ajacis. The cut spikes of C. ajacis were supplemented with various SA treatments viz, 2 mM, 4 mM, 6 mM. The effects of these treatments were evaluated against control set of spikes placed in distilled water. Our study indicates considerable increment in postharvest longevity of cut spikes, besides an increase in solution uptake, sugar and protein content of tepal tissues.SA augmented antioxidant system via upsurge in phenolic content and antioxidant enzymes viz, superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) to forfend reactive oxygen species (ROS) related oxidative damage. SA profoundly reduced lipoxygenase (LOX) activity to preserve the membrane integrity and thus prevented seepage of solutes from tepal tissues. These results authenticate SA particularly 4 mM concentration as effective postharvest treatment to preserve the postharvest quality of C. ajacis cut spikes.     

Field Tests of Formulated Products Containing EitherVerticillium chlamydosporiumorArthrobotrys dactyloidesfor Biological Control of Root-knot Nematodes

Granular formulations containing eitherVerticillium chlamydosporiumorArthrobotrys dactyloideswere applied at 55–880 kg/ha in seven field trials on a range of soils in Queensland, Australia. Granules were incorporated into soil prior to planting tomatoes and the effectiveness of the formulated fungi in reducing damage caused by root-knot nematodes was compared to an untreated control and a granular formulation of fenamiphos. Formulations ofV. chlamydosporiumwere used in three experiments but the fungus did not increase egg parasitism or reduce galling or nematode numbers at harvest. Formulations containingA. dactyloideswere more effective, as galling was reduced 4–8 weeks after planting in four of five experiments. However, these effects generally disappeared later in the season, as significant reductions in galling were only observed in one of seven experiments at harvest. Fenamiphos generally reduced galling both at 4–8 weeks and at harvest. Yield increases due to fenamiphos or any of the biological treatments were not obtained in any experiment. The results suggested that formulations ofA. dactyloidesapplied at 220–440 kg/ha substantially reduced the number of nematodes present in roots 4–8 weeks after planting. Since tomato is relatively tolerant of nematode damage under the crop management systems used in northeastern Australia, such formulations could provide useful nematode control, particularly if used in conjunction with other control measures. However, formulations with greater biological activity will be needed if the level of nematode control obtained with chemical nematicides is to be achieved withA. dactyloides.     

Effects of Preharvest Applications of CaCl2, 2,4-D and Benomyl and Postharvest Hot Water, Yeast and Fungicide Treatments on Development of Decay on Satsuma Mandarins

In this study, an integrated approach was evaluated for the control of postharvest decays of mandarin including some pre‐ and post‐harvest treatments under storage conditions. The efficacy of the treatments both as alone and in combination was evaluated during 3 years. Preharvest application of benomyl resulted in significantly less decay of mandarin fruit after storage in 3‐year tests. Calcium chloride (CaCl₂), 2,4‐dichlorophenoxyacetic acid (2,4‐D) and gibberellic acid (GA₃) as stand‐alone treatments or combinations were not effective in controlling Penicillium and total decay infections on inoculated mandarin. Postharvest application of imazalil (200 μg/ml) in solution heated to 54°C for controlling postharvest green and total decay of mandarin was significantly effective for 3 months under storage conditions. The biocontrol activity of yeast (Metschnikowia pulcherrima) was improved when yeast treatment was combined with imazalil (200 μg/ml) at postharvest. The data suggest that preharvest application of benomyl and postharvest treatments of imazalil, hot water and yeast may reduce postharvest green mould and total decay of mandarin under storage conditions.