Changes in free amino acid concentrations in mycorrhizal strawberry plants

The influence of arbuscular mycorrhizal fungi (AMF) colonization on free amino acid concentrations in strawberry (Fragaria × ananassa Duch., cv.Nohime) plants was investigated using two AMF species [Glomus mosseae (Gm), Gl. aggregatum (Ga)] under phosphorus-supplemented (+P) or non-supplemented (−P) conditions. Ten weeks after AMF inoculation, mycorrhizal plants showed higher values in dry weight of both shoots and roots than did non-mycorrhizal ones among most of the treatments. Shoots and roots of mycorrhizal plants had greater phosphorus concentrations in −P plots, while in +P plots, P concentrations differed little among the inoculation treatments. AMF colonization was greater in plants inoculated with Gm than in plants inoculated with Ga. Total amino acid concentration was higher in most of the plants inoculated with Gm than in non-mycorrhizal ones regardless of P treatment. Serine, glutamic acid, glycine, alanine, leucine and GABA were higher in both mycorrhizal plants in −P plots than in non-inoculated plants. In +P plots, threonine and isoleucine concentrations were greater in both mycorrhizal plants than in non-inoculated ones. Asparagine, glutamic acid, glycine, citrulline, GABA and arginine were greater in plants inoculated with Gm than in non-mycorrhizal ones. These findings verified that inoculation with AMF increases total amino acid concentrations and concentrations of specific amino acids in strawberry plants with or without phosphorus supplementation, though the effects varied with species of mycorrhizal fungus.     

Crown branching and cropping potential in strawberry (Fragaria ananassa Duch.) can be enhanced by daylength treatments

Summary

When strawberries (Fragaria ananassa Duch.) are produced in a greenhouse, usually two crops a year are obtained; in the fall and in the spring. To increase productivity, new cultivation techniques are needed. The aim of this study was to examine the effect of daylength treatments on the performance of strawberry plants to improve plant production protocols. The possibility of obtaining two successive crops during forcing was explored by exposing plants of cultivar Korona to two successive short day (SD) treatments followed by cold storage. The following daylength treatments were studied: 3 wk SD + 2 wk long day (LD) + 3 wk SD (3SD2LD3SD), 3 wk SD + 4 wk LD + 3 wk SD (3SD4LD3SD), and 10 wk SD (10SD). In addition, crown branching was studied in plants subjected to SD treatments. Two successive SD treatments enabled two successive flowering and cropping periods during greenhouse forcing after eight weeks of cold storage.The first SD treatment caused crown branching and induced flowering in the apical meristem of the main-crown and in the oldest axillary meristem(s), whereas younger axillary meristems were induced during the second SD treatment. Marketable yield and the number of inflorescences were comparable in 3SD4LD3SD and 10SD, but considerably lower in 3SD2LD3SD. However, this study demonstrated the high cropping potential of artificially SD treated plants, which makes them a potential alternative for greenhouse strawberry cultivation. Multi-crowned plants of ‘Korona’ can be produced by subjecting young plants to a three week SD treatment, and crown branches can be induced to flowering by a new SD treatment resulting in a very high cropping potential. Induced plants can be stored at –1°C for later forcing.     

Field response of papaya (Carica papaya L. cv. Coorg Honey Dew) to inoculation with arbuscular mycorrhizal fungi at different levels of phosphorus

Summary

Papaya (Carica papaya L.) cv. Coorg Honey Dew is one of the most popular cultivars grown in Southern India, but it requires high doses of inorganic phosphorus (P) fertilisation for growth. Arbuscular mycorrhizal fungi (AMF) are known to improve plant growth and nutrient uptake, especially the uptake of P and micronutrients. As papaya plants respond well to high levels of P, inoculation with AMF was studied to see if AMF could fulfill the requirement for P in plants grown under field conditions. Papaya seedlings (n = 36 per AMF) were colonised separately, in polybags, for 45 d by two species of AMF, Glomus mosseae and G. fasciculatum. Seedlings were then transplanted to the field, with uninoculated seedlings as controls, in a replicated randomised block design. Three levels of P were applied [50, 75, or 100% of the recommended dose (240 g plant^–1 year^–1) of P fertiliser, as super-phosphate]. Plants were studied for root colonisation by AMF, for growth parameters, and for leaf nutrient contents (especially, P, Zn, and Cu). Acidic and alkaline phosphatase activities in the roots of AMF-colonised plants were recorded as these enzymes are involved in the mobilisation of P. The yields of plants up to 18 months-old, and fruit quality, measured by total soluble solids contents (TSSC) and β-carotene contents, were recorded. AMF-inoculated plants performed better than uninoculated control plants at all levels of P applied. G. mosseae was more effective at improving plant growth, fruit yield, and P and Zn contents than G. fasciculatum at the 75% and 50% P-levels. Cu contents increased at all P-levels in G. fasciculatum-colonised plants. Total soluble solids contents showed marginal improvements at the 75% P level with both fungi. β-carotene contents increased significantly in G. mosseae-colonised plants at the 50% and 75% P-levels, and in G. fasciculatum-colonised plants at the 75% P-level. The feasibility of applying on-farm produced AMF inoculum to improve papaya cultivation and to save 25% of the P applied during papaya cultivation is discussed.     

Morpho-Physiological Responses of Grape Rootstock ‘Dogridge’ to Arbuscular Mycorrhizal Fungi Inoculation Under Salinity Stress

Effects of arbuscular mycorrhizal fungi (AMF) alone or in combination with bacterial consortium (AMF+BC) inoculation prior to induced salinity (NaCl @ 150 or 250 mM) were studied on root growth; plant biomass; leaf area; Na⁺ and K⁺ contents; leaf water potential (Ψ_w); osmotic potential (Ψ_π); photosynthesis rate (P_n); and contents of chlorophyll, phytohormones, and polyamines in the grape rootstock ‘Dogridge’, popular among Indian vine growers. AMF inoculation in the NaCl untreated rootstocks plants increased root growth, root and shoot biomass, and leaf area and improved leaf Ψ_w, Ψ_π, P_n, and chlorophyll content, and also countered the stress-induced decline in the NaCl treated plants. The abscisic acid (ABA), cytokinins, and polyamine-spermidine and spermine contents in the leaves of NaCl untreated or treated were significantly increased by the AMF inoculation. Among the treatments, AMF with BC was relatively more effective than AMF alone with respect to changes in above morpho-physiological characters. The results depicted that AMF (AMF alone or AMF+BC) inoculation significantly improved salinity tolerance of grape rootstock and tolerance is induced by improvements in plant water balance, K⁺:Na⁺ ratio, and P_n, besides distinct accumulations in ABA and polyamines-spermine and spermidine. The above findings have potential in suggesting the AMF usefulness in improving the efficacy of ‘Dogridge’ rootstock in grape cultivation under salt affected soils.     

Effects of pavements on diversity and activity of mycorrhizal symbionts associated with urban trees

This study investigated the impact of different types of soil sealing on the communities of a group of beneficial plant symbionts, arbuscular mycorrhizal fungi (AMF), colonizing the roots of two shade trees, Celtis australis and Fraxinus ornus, frequently grown in urbanized sites. Such plants were grown in an experimental site, in northern Italy, established in November 2011 and subjected to four different pavement treatments: impermeable monolithic asphalt, permeable pavers, permeable concrete and unpaved soil. The diversity and composition of root AMF communities were assessed by PCR denaturating gradient gel electrophoresis of partial 18S rRNA gene, AMF taxa were identified by amplicon sequencing and mycorrhizal colonization was evaluated after root clearing and staining. For the first time, our molecular work revealed that impermeable pavements induced shifts in the composition of AMF communities associated to the roots of C. australis and F. ornus and impacted on the percentage of mycorrhizal root length. When the root-zone was covered with permeable pavements, a similar AMF community as that observed in the unpaved soil was detected, providing novel information to be utilised for reducing the disturbance caused by specific types of soil sealing on AMF symbionts, which play a key role in plant nutrition and health. A total of 45 AMF sequence types were detected, with Sclerocystis and Septoglomus as the most abundant phylotypes, accounting for 84% of the sequences. The predominance of Sclerocystis species in the roots of both tree species under impermeable pavements indicated their high and unforeseen tolerance towards harsh environmental conditions. Such species could be utilized as AMF inocula specifically selected for their proven resilience in paved sites, in order to exploit their ability to boost biogeochemical processes fundamental for energy fluxes and plant nutrition and health.     

Selection of arbuscular mycorrhizal fungi for citrus growth promotion and Phytophthora suppression

In order to reduce unnecessary amount of P-fertilizer and severity of Phytophthora root rot in citrus orchards, the experiment was set up. Thirteen indigenous arbuscular mycorrhiza (AM) fungi species were isolated from rhizosphere soil of citrus orchards in Thailand and were then propagated into three host plants [sorghum (Sorghum bicolor), maize (Zea mays), and leek (Allium cepa)] by trap culture. We also tested whether indigenous AMF species (13 different species) could colonize into three cultivars of citrus scions and rootstocks (Shogun: Citrus reticulata Blanco cv. Shogun; Tangerine: C. reticulata; and C-35 citrange: Citrus sinensis × Poncirus trifoliata). With root colonization rates, the results indicated that Acaulospora tuberculata and Glomus etunicatum provided the best colonization in all citrus cultivars. We selected, therefore, those AMF species to verify their influences on citrus growth and Phytophthora root rot resistance. Three cultivars of citrus scions and rootstocks, Shogun, Tangerine and C-35 citrange, were inoculated with two effective indigenous AMF species, G. etunicatum or A. tuberculata in order to determine the influences on citrus growth. The plants were investigated to determine the mycorrhizal efficiency index (MEI), AM colonization, P content, and other parameters. Co-inoculation of AMF species (G. etunicatum or A. tuberculata) with Phytophthora nicotianae was also carried out in Shogun scion/C-35 citrange rootstocks. The results of citrus growth revealed that Shogun and Tangerine inoculated with G. etunicatum produced the highest MEI. Tangerine and C-35 citrange amended with fertilizers and G. etunicatum showed the highest P content in leaves. This indicated that G. etunicatum has an influence on citrus growth and P uptake, suggesting it to be the highly effective strain. Shogun scion/C-35 citrange rootstock combinations that were inoculated by both P. nicotianae and different AM fungi (G. etunicatum or A. tuberculata) showed root injury at low level of root rot symptom. However, the part of Shogun scions grafted on rootstocks showed severe symptom of shoot die back in treatment inoculated with P. nicotianae alone, while treatment inoculated with different AM species (G. etunicatum or A. tuberculata) and P. nicotianae rendered lower shoot die back symptoms than that of Phytophthora treatment. The low level of shoot die back symptom was shown at first, then healthy young shoot was restored. Our results indicated the facts that different host plants and different AMF species produced different outcomes of growth and pathogen resistance. The application of both AM isolates, therefore, has an enormous potential to be produced the inoculum for citrus orchards.     

Effects of AMF inoculation on growth of Panax ginseng C.A. Meyer seedlings and on soil structures in mycorrhizosphere

We aimed to investigate the effects of inoculating Panax ginseng C.A. Meyer seedlings with arbuscular mycorrhizal fungi (AMF) by examining the root colonization, plant nutrition uptake, growth characteristics, and soil aggregation of P. ginseng seedlings inoculated at the time of transplantation. At 16 weeks, the AMF spore density per 30 g of fresh mycorrhizosphere in seedlings inoculated with AMF (AMF+ seedlings) was 256.8 and that in seedlings not inoculated with AMF (AMF− seedlings) was 186.3, respectively. The colonization rate of AMF in the lateral roots of AMF+ seedlings was approximately 19% higher than that in the lateral roots of AMF− seedlings. The patterns of AMF colonization in ginseng roots were similar to those of the Paris-type mycorrhizal association. Plant growth characteristics, such as plant height, root length, leaf area, number of lateral roots, fresh weight of shoots and roots, and chlorophyll content, were significantly enhanced in AMF+ seedlings compared to AMF− seedlings. The macronutrient content (P, K, and Ca) and micronutrient content (Cu, Fe, and Zn) of both shoots and roots were also significantly higher in AMF+ seedlings compared to AMF− seedlings. Furthermore, glomalin content and soil aggregation were significantly enhanced in AMF inoculated areas. Our results indicate that AMF inoculation may enhance the growth of ginseng seedlings by improving the uptake of mineral nutrients and the soil structure in mycorrhizosphere.     

Responses of some different pepper (Capsicum annuum L.) genotypes to inoculation with two different arbuscular mycorrhizal fungi

Eight different pepper genotypes inoculated by two different arbuscular mycorrhizal fungi (AMF) [Glomus intraradices (Gi) and Gigaspora margarita (Gm)] in a growth chamber experiment under normal seedling growing conditions were evaluated for seedling traits, colonization and relative mycorrhizal dependency (RMD). In general, inoculated plants had greater dry weights compared to non-inoculated plants. Five cultivars responded positively to inoculation with AM fungi and three responded negatively. A great variation in mycorrhizal colonization dependency was observed among the pepper genotypes, with the N52 genotype showing the highest RMD and the Karaisali genotype the lowest. RMD and dry weights of pepper genotypes were inversely correlated.     

The Effect of a Substrate Containing Arbuscular Mycorrhizal Fungi and Rhizosphere Microorganisms (Trichoderma,Bacillus, Pseudomonas and Streptomyces) and Foliar Fertilization on Growth Response and Rhizosphere pH of Three Strawberry Cultivars

Abstract

Vegetatively propagated plants of three strawberry cultivars-‘Senga Sengana’, ‘Elsanta’ and ‘Kent’-were grown for 20 weeks in rhizoboxes filled with 1.85 kg of sterilized mineral soil. Ten plants were treated with an N-P-K foliar fertilizer (F, control), or inoculated with a substrate containing arbuscular mycorrhizal fungi, Trichoderma viride and rhizosphere bacteria (PGPR-Plant Growth Promoting Rhizobacteria) without any fertilization (M), or inoculated with the mixture of microorganisms and treated with the foliar fertilizer (MF). Total plant biomass was increased by the M treatment in all cultivars. M treatment resulted in higher total root length and number of root tips in ‘Senga Sengana’, whereas the other two cultivars showed different responses of root morphology. Shoot/root ratio was decreased by the M and MF treatments in comparison with control plants. Foliar fertilization of inoculated plants caused different growth responses in the three cultivars and a general decrease of root growth. After the MF treatment, the biomass of ‘Senga Sengana’ increased and the biomass of ‘Elsanta’ and ‘Kent’ decreased. Inoculation with the mycorrhiza-PGPR substrate increased rhizosphere pH irrespective of foliar fertilization. Plant mineral content was highly modified by the treatments in all the cultivars examined. In particular, changes were noted in N, P, K, Fe, B and Mn uptake. The results show an interaction between foliar fertilization and root inoculation with microorganisms, as well as genotype-dependent influences, on growth responses and rhizosphere pH of strawberry plants.     

Anaerobic Soil Disinfestation and Brassica Seed Meal Amendment Alter Soil Microbiology and System Resistance

ABSTRACT

Brassica seed meal amendments and anaerobic soil disinfestation (ASD) control a spectrum of soil-borne plant pathogens via a diversity of mechanisms. Transformations in microbial community structure and function in certain instances were determinants of disease control and enhanced plant performance. For instance, in strawberry field soils, increased strawberry yields in response to ASD were attained in a carbon-source input-dependent manner. ASD conducted with rice bran as the carbon input, but not molasses, resulted in significantly greater yields. Effective ASD treatments, but not ineffective treatments, resulted in increased abundance of bacteria in phylum Bacteroidetes in treated soils, specific genera of which are known to provide biological disease control. Brassica seed meal amendment resulted in development of a soil system suppressive towards disease incited by the root pathogen Macrophomina phaseolina. Brassica seed meal treated orchard soil systems exhibit resistance to re-infestation by soil-borne pathogens, including the plant parasitic nematode Pratylenchus penetrans. System resistance is associated with significant and prolonged changes in rhizosphere microbiology and specifically amplification of specific organisms with potential to parasitize P. penetrans.     

缺钾胁迫对连作草莓生长和土传病害的影响

 以草莓‘红颜’品种为试材,设缺K（K+ 48.75 mg · L^-1,缺量水平）、1/2K（K+ 415.58 mg · L^-1, 半量水平）和全量K（K+ 782.41 mg · L^-1,正常水平）营养液处理,对缺钾胁迫与草莓连作障碍的关系进 行了探讨。结果表明,缺钾处理显著抑制二茬草莓植株地下部分和地上部分的生长,其中缺K 的长势最 弱,1/2K 比全量K 的长势强;缺K 二茬植株根系分泌物对草莓组培苗生长有显著影响,表现为低浓度（1%、 2%）根系分泌物促进幼苗侧根和茎叶生长,高浓度（4%）则抑制根系生长。不同浓度钾营养液处理的三 茬植株分别接种尖孢镰刀菌和大丽轮枝菌后,在不同时期比未经过连作的基质对照发病都严重。缺K 三 茬植株发病最重,接菌后10 d 时病情指数就高达75,全量K 三茬植株发病次之,1/2K 三茬植株发病相 对较轻。因此,缺K 环境会加重草莓的连作障碍,适宜的K 量对草莓连作障碍的防治有重要意义。     

Status of Macrophomina phaseolina on Strawberry in California and Preliminary Characterization of the Pathogen

ABSTRACT

Macrophomina crown and root rot has become a significant soil-borne disease issue in California. For many locations in the state, the disease is associated with fields that are no longer pre-plant, flat field fumigated with methyl bromide + chloropicrin. Inoculation experiments indicated that some differences in strawberry cultivar susceptibility to Macrophomina phaseolina were seen a short time after the inoculation, but as disease progressed such differences did not persist. Preliminary characterization studies of Macrophomina phaseolina isolates from strawberry indicated that such isolates may have a host preference for strawberry. Macrophomina phaseolina isolates from watermelon, thyme, and apple failed to cause disease in strawberry. Five cover crop species, which can be rotated with strawberry, did not develop disease when inoculated with strawberry isolates. In preliminary analysis using simple sequence repeat markers, isolates obtained from strawberry formed a separate group compared to isolates recovered from other known Macrophomina phaseolina hosts.     

Evaluation of Strawberry Genotypes for Chaetosiphon fragaefolii (Strawberry Aphid) Preference

ABSTRACT

Thirty-one strawberry genotypes were evaluated for supporting the reproductive success of the strawberry aphid (Chaetosiphon fragaefolii), a vector of several strawberry viruses. A pure colony of C. fragaefolii was initiated from eggs collected from field strawberry leaves in Fall 2013. In Spring 2014 greenhouse-grown strawberry plants with four to five leaves were placed in screened cages (16 genotypes/cage) and five aphids were placed on each plant. After 30–32 days, the number of aphids in each of four developmental stages was counted on each plant. Total aphid numbers/plant ranged from a mean of 33 on Fragaria chiloensis CFRA 48 (PI 551459) to 279 on F. × ananassa ‘AAC Lila’. Cultivars with relatively low numbers of aphids included ‘Bounty’ (106 aphids), ‘Mira’ (114 aphids), and ‘Annapolis’ (115 aphids). This experiment, part of a larger project on aphids and virus diseases associated with the cultivated strawberry, will inform decisions in the strawberry breeding program.     

日光温室草莓基质栽培与有土栽培比较试验

对日光温室草莓基质栽培追施有机固态肥、液态肥的栽培效果进行研究,调查了该栽培方式下'甜查理'草莓的营养生长情况和果实品质,并与采用相同施肥措施的有土栽培植株进行了比较.结果表明:基质栽培草莓的植株生长势与有土栽培的基本一致,果实可溶性固形物、钙、铁含量及糖酸比有所提高,而果实平均单果重、果实还原糖、总酸、蛋白质、Vc、钾的含量略有下降,但与有土栽培的果实差异不大.该基质栽培方式管理简便,效果较好,可以作为防治草莓重茬的有效措施进行进一步的研究利用.     

Isolation of arbuscular mycorrhizal fungi and Azotobacter chroococcum from local litchi orchards and evaluation of their activity in the air-layers system

Soil samples were collected from rhizosphere of litchi-growing areas of North-Western Himalayan Region (NWHR) of India, for finding qualitative and quantitative differences in arbuscular mycorrhizal (AM) fungi and Azotobacter chroococcum. These samples were taken from plants being grown in different cultivation types namely, weed control with weedicides or tillage; orchard floor either clear or with cover crops; intercropping with cereals and legumes. Qualitative and quantitative differences were noticed with different cultivation types and a marked reduction in the AM fungi was observed in orchards where chemicals were used for weed control and intensive farming system was used on the orchard floor. AM fungi were generally abundant in the soils with range pH 5.5–6.6. Among different AM fungi retrieved from the soils, Glomus spp. was most dominant. Fifteen AM fungal species were isolated, identified and characterized and along with their ability to colonize the roots. In the soil samples, a marked variation in viable bacterial count of A. chroococcum was also noticed due to varied physico-chemical characteristics of the orchard soils. The changes in AM fungal species composition can be attributed to changes in soil chemical properties resulting from cultural practices such as ploughing, application of chemical fertilizers and weedicides. An experiment was also conducted to study the comparative efficacy of four dominant and frequently occurring indigenous AM species namely, Glomus fasciculatum (Thaxter sensu Gerdemann), G. magnicaulis (Hall), G. mosseae (Nicol. & Gerd.), Gigaspora heterogamma (Nicol. & Gerd.) and two A. chroococcum strains viz., AZ₁ and AZ₂ singly and in dual combination to evaluate their effect in air-layers system. Dual inoculation of G. fasciculatum and AZ₁ increased total root length of air-layered shoots by 81.39% over uninoculated control. These studies indicated that indigenously isolated AM fungal species and A. chroococcum strains can be used for air-layering for better adaptation under specific agro-climatic and ecological zone conditions.     

接种丛枝菌根真菌对草莓基质育苗生长及果实品质的影响

以从日本引进的“天皇御用”草莓品种为试材,在日光温室条件下研究了接种丛植菌根真菌对草莓苗期生长及果实品质的影响.结果表明:接种丛枝茵根真菌显著提高了草莓苗期株高、叶柄长及根冠比.单果重增加8.76％,草莓果实维生素C含量、可溶性糖含量均有提高,而可滴定酸含量有所下降,从而提高了草莓品质,改善了草莓风味.     

Autotetraploid Green Watercress

Auxin-phloroglucinol synergism has been observed to promote the rooting of the Rubus hybrid (R. ursinus Cham, and Schlectxß. idaeus L.) but not the perpetually fruiting strawberry cv Gento Hummell (a hybrid of Fragaria virginiana Duchesne xF. chiloensis Duchesne). In strawberry PG was successfully substituted for IBA but the presence of both IBA and PG reduced rooting compared with other treatments. In strawberry PG affected the organization of tissues and the pattern of root branching; no callus was formed and growth of second order laterals was enhanced. Promotive effects of PG on leaf development were observed in both species but their effects may be indirect since root development was enhanced in treatments that also stimulated leaf growth. In both Rubus and strawberry the non-indole auxin a α-naphthaleneacetic acid showed no synergistic effects with PG on leaf and root development. These results demonstrate that the growth promotive effects of PG are not specific to Malus species.     

丛枝菌根真菌和促生细菌对草莓生长、产量和白粉病的影响

以“章姬”“京藏香”“京桃香”3个品种的草莓为试材,采用盆栽试验的方法,研究接种丛枝菌根真菌(arbuscular mycorrhiza fungi,AMF)摩西斗管囊霉Funneliformis mosseae、根内根孢囊霉Rhizophagus intraradices、植物根围促生细菌(plant growth-promoting rhizobacteria,PGPR)PGPR 5-1和PGPR PS1-1菌株对草莓生长、产量和白粉病的影响。结果表明:AMF+PGPR处理的AMF侵染率、丛枝着生率和泡囊数均大于单接种AMF处理,表明PGPR菌株能够促进AMF的侵染和根内扩展;AMF+PGPR组合促生防病的效应大于任一单接种处理。其中,Fm+PS1-1和Fm+5-1′组合促生、增产和控制白粉病的效果最好。“章姬”草莓的接种效应大于其它2个品种的接种效应。Fm+PS1-1处理显著增加了“章姬”草莓的单株花蕾数、单株开花数、单株结果数和单株产量,单株产量最高达到75.8g,而白粉病的病情指数最低。可知,Fm+PS1-1和Fm+5-1′为最佳组合,对促进草莓高效高质绿色生产具有较大的应用潜力和研发前景。     

Efficacy of Insecticides against Lygus hesperus Knight (Hemiptera: Miridae) in the California’s Central Coast Strawberry

ABSTRACT

The western tarnished plant bug, Lygus hesperus Knight (Hemiptera: Miridae), is an important insect pest of strawberry (Fragaria ananassa Duchesne) in the Central Coast of California. Because little is known about efficacy of new insecticides, especially sulfoxaflor and flupyradifurone, against L. hesperus, two replicated insecticide experiments were conducted in 2014 and 2015 in commercial strawberry fields naturally infested with L. hesperus. The insecticides, sulfoxaflor, flupyradifurone, flonicamid, thiamethoxam fenpropathrin, essential oils (rosemary and peppermint oils), and mineral oil, were compared with untreated check. Higher and lower rates of flupyradifurone and sulfoxaflor were tested. Higher rates of sulfoxaflor and flupyradifurone were effective in suppressing L. hesperus. The industry standard, thiamethoxam + fenpropathrin, was effective in 2014 but not in the 2015 experiment. Flonicamid provided a moderate level of efficacy against L. hesperus in both years. The number of predacious bugs was significantly lower in the higher rate of flupyradifurone than in other treatments, although the number of spiders was not significantly different among treatments.     

Optimum Level of Nitrogen and Phosphorus to Achieve Better Papaya (Carica papaya var. Solo) Seedlings Growth and Mycorrhizal Colonization

An experiment under greenhouse conditions was carried out to evaluate the best level of nitrogen (N) and phosphorus (P), which promote the growth of papaya (Carica papaya L. var. Solo) seedlings without affecting the arbuscular mycorrhizal fungi (AMF) activity. Seedlings of papaya were transplanted to pots inoculated or not with Gigaspora margarita spores at four levels of N (0, 50, 100, and 200 ppm) and P (0, 25, 50, and 100 ppm). P was amended at the same time of pot filling up with substrate but N was applied weekly. The experiment was harvested after 100 days and plant dry weight together with AMF colonization was measured. The major response on the plant dry weight and height was from the fertilizers (N and P) where it proportionally increased. For the dry weight, at low amounts of nutrients the effects of AMF were greater, but as much as the fertilizer level in soil increased this response decreased. The colonization decreased as the nutrient levels increased, especially the P. The best combination of N and P for plant growth and AMF colonization could be at 50 and 25 ppm, equivalent to 5 and 2.5 kg/10a, respectively.