Nursery Pots Research Articles

USING SNPS FOR TRANSPLANTING OF COTTON SEEDLINGS TO INCREASE PLANT GROWTH AND YIELD

Straw nursery pots (SNPs), which utilize agricultural residues such as wheat straw and corn stalks as raw materials, can be widely used in the transplanting of seedlings of crops, vegetables, flowers and trees. Plastic nursery pots (PNPs) and direct sowing (DS) were used as controls in evaluating the effects of SNPs on plant growth, dry matter partitioning, yields and economic benefits of transplanted cotton. SNPs significantly increased the rate of emergence, shortened the convalescent period by about 7 d and increased the transplant survival rate by 8.8% compared to PNPs. This led to significantly increased dry matter accumulation: that of reproductive parts for SNP seedlings were 1.5- and 1.8-fold of that for PNPs and DS, respectively. The lint yield using SNPs was 11.5 and 17.5% greater than for PNPs and DS, respectively. Boll number per plant with SNPs was 7.5 and 23.3% greater than for PNPs and DS, respectively; lint weight was not significantly different than with PNPs and was 5.8% greater than for DS. There were no significant differences in lint percentage among the three systems. Further benefit analysis showed that net revenue per hectare from using SNPs in cotton production was US$108 and US$279 greater than for PNP and DS, respectively. This was mainly due to significantly increased output, a reduced number of seedlings needed, nursery pot costs accounting for a relatively small proportion of total investment, and the relatively low labor costs in China.

First Record of Alfalfa mosaic virus in Teucrium fruticans in Italy.

The Teucrium genus (Lamiaceae family) contains ~300 species of evergreen and deciduous shrubs with some species widely used as ornamental plants in rock gardens. During the springs of 2010 and 2011, some plants of Teucrium fruticans L., also known as "tree germander", growing singly in pots in a Ligurian nursery (Savona Province, northern Italy), were noted for a bright yellow calico mosaic on the leaves (~1% of ~2,000 plants inspected exhibited symptoms). Preliminary electron microscope observations of leaf-dips showed semispherical to bacilliform particles, consistent with Alfamovirus and Oleavirus, in preparations obtained only from leaves of symptomatic plants. Three symptomatic and two asymptomatic plants were checked for Cucumber mosaic virus or Alfalfa mosaic virus (AMV) in protein A sandwich (PAS)-ELISA with commercial kits (Bioreba, Reinach, Switzerland) and Olive latent virus 2 (OLV2) by immunodecoration of virus particles with an OLV2 antiserum produced against an Italian OLV2 isolate. Symptomatic plants were positive only to AMV and all asymptomatic plants were negative to all viruses checked. The virus was successfully transmitted mechanically to Chenopodium amaranticolor and Ocimum basilicum that reacted, as expected for infections caused by AMV (1), with a chlorotic local lesion followed by mosaic and bright yellow mosaic, respectively. The disease was transmitted also by grafting an infected scion on healthy T. fruticans. Symptoms appeared after ~3 weeks in one plant of six grafted. AMV infection in a symptomatic grafted plant was verified by PAS-ELISA, confirming that bright yellow mosaic symptoms observed in T. fruticans were induced by an isolate of AMV. Immunocapture reverse transcription (IC-RT)-PCR assay, following the protocol described by Wetzel et al. (4), was performed on leaf extracts from one symptomatic plant using a polyclonal serum raised against a French isolate of AMV, provided by H. Lot (INRA, Station de Pathologie Végétale, Avignon, France). Specific AMV primer pair was used in the RT-PCR reactions (2). A DNA fragment of ~750 bp, covering the entire coat protein gene (CP), was obtained after IC-RT-PCR. The amplicon was gel purified with the Wizard SV Gel and PCR Clean-Up System (Promega, Madison, WI), cloned into pGEMT-easy vector (Promega) and two independent clones sequenced on both strands at MWG Biotech (Ebersberg, Germany). The consensus sequence was submitted to EMBL (No. FR854391). Pairwise comparison of the AMV-T. fruticans isolate CP sequence (named Tef-1) with those of AMV reference isolates revealed the maximum (98.0 to 97.3%) nucleotide identities with isolates belonging to subgroup I, 95.5 to 94.0% identities with subgroup IIA isolates, and 95.6% identity with the subgroup IIB isolate Tec-1 (3). Among subgroup I isolates, Tef-1 had the maximum CP nucleotide identity with the CP gene belonging to an AMV isolate identified in 2010 in Lavandula stoechas in the same geographic area, suggesting a common origin for these two viral isolates. Overall results clearly indicate that an AMV isolate was the causal agent of the calico-type mosaic observed in T. fruticans. To our knowledge, this is the first report of T. fruticans as a natural host of AMV.

Nursery pot application and planting hole application using controlled-release fertilizers able to reduce the amount of fertilizer in Greenhouse horticulture(JSSPN Technological Advancement Progress Awards)

Nursery pot application and planting hole application using controlled-release fertilizers able to reduce the amount of fertilizer in Greenhouse horticulture(JSSPN Technological Advancement Progress Awards)

First Report of White Pine Blister Rust Caused by Cronartium ribicola on Immune Black Currant Ribes nigrum Cv. Titania in Preston, Connecticut.

Since the relaxation of federal sanctions on the planting of Ribes crops because of the development of white pine blister rust (WPBR) immune Ribes cultivars (3), a small industry for the production of Ribes fruit for fresh and processing markets was established in New York and surrounding New England states. The majority of Ribes acreage in the region is planted to a WPBR immune black currant R. nigrum cv. Titania. From 2008 to June 2011, symptoms resembling those caused by WPBR pathogen Cronartium ribicola were observed at a large (>12 ha) R. nigrum cv. Titania planting in Preston, CT. In 2008, infection was restricted to a single field (100% incidence), but in 2009, all fields suffered from premature defoliation by late July. In 2010 and 2011, there was considerable incidence (>85%), but premature defoliation was kept in check by chemical management. Symptoms began as chlorotic lesions (0.5 to 4.3 mm in diameter) on both sides of the leaf. These chlorotic lesions had margins delineated by leaf veins and many developed necrotic (0.3 to 0.9 mm in diameter) centers on the upper surface of leaves within 2 to 3 weeks. The undersides of lesions developed blisters containing orange uredinia (0.1 to 0.33 mm in diameter) with smooth peridia that broke with the production of yellow-orange urediniospores (30 × 15 to 25 μm). Symptoms and signs were consistent with published descriptions of C. ribicola (1) and with WPBR infections on highly susceptible R. nigrum cv. Ben Alder planted at the New York State Agricultural Experiment Station in Geneva. Additional confirmation was provided by sequencing the two internal transcribed spacer (ITS) regions and the 5.8S gene (GenBank Accession No. JN587805; 98% identity with No. DQ533975) in the nuclear ribosomal repeat using primers ITS1-F and ITS4 as described previously (2,4). Furthermore, an attempt was made to confirm pathogenicity in the greenhouse by inoculating shoots of potted nursery stock of R. nigrum cv. Titania. Shoots were inoculated by rubbing leaves with either an uninfected currant leaf or a currant leaf from Preston, CT sporulating with urediniospores. Plants were subsequently misted with dH20 and covered with plastic bags for 24 h. Plants were watered biweekly and kept in a greenhouse with 39 to 65% relative humidity at 21 to 26°C. Shoots were monitored for symptom development on a weekly basis. After 3 weeks, 2 of the 10 plants inoculated with infected leaves developed chlorotic lesions and uredinia identical to those on leaves from Preston, CT, while all others remained healthy. Although not easily reproducible in a greenhouse, the breakdown of immunity in R. nigrum cv. Titania was observed for the last 4 years in Connecticut. Given that WPBR immunity was one of the conditions for legalized planting of Ribes, the breakdown of immunity has potentially deleterious implications particularly for nearby states like Massachusetts and New York, in which the Ribes industries are expanding. Moreover, Ribes growers may need to rely on chemical management programs to manage WPBR in the future.

Bait Insecticides and Hot Water Drenches Against the Little Fire Ant,Wasmannia auropunctata(Hymenoptera: Formicidae), Infesting Containerized Nursery Plants

Broadcasts of hydramethylnon, S-methoprene, and metaflumizone baits, metaflumizone spray, and hot water drenching were evaluated for their efficacy against the little fire ant, Wasmannia auropunctata (Roger), in potted nursery plants. Two applications one month apart of either a bait containing 0.365% hydramethylnon and 0.25% S-methoprene (Extinguish Plus) or a spray containing 24% metaflumizone (BAS 320 I 240 SC) reduced foraging worker numbers by >97% as compared with untreated controls. The persistence of weather-exposed metaflumizone (0.063%) bait was also evaluated: bait applied fresh or after 7 days of weather exposure resulted in >98% ant mortality; bait exposed to weather for 14 d before application still achieved >90% mortality. In vitro submersion of W. auropunctata in 45°C water for 10 min resulted in >99% mortality as compared with 28.9% mortality from submersion in ambient temperature water (26°C) for 12 min. When W. auropunctata -infested potted plants were drenched with hot water (45.6°C) for 11 min, the number of live ants were reduced by 99.3 and 89.3% in rhapis and fishtail palm, respectively, as compared with control plants drenched with ambient temperature water. The presence of a single W. auropunctata worker in a potted plant would fail to meet export requirements; therefore, the chemical baits and sprays and hot water treatment (45.6°C for 11 min) as evaluated in this study would not individually be a sufficient quarantine protocol against little fire ants in containerized nursery plants.

Alternaria alternata causes pre-harvest discolouration in Backhousia myrtifolia leaf

Backhousia myrtifolia is an Australian native plant cultivated for cut flowers and foliage. A leaf browning syndrome, with unknown cause, became problematic for the floriculture industry in the years 2003–2004. Alternaria alternata was isolated consistently from brown leaf lesions on potted nursery plants and pathogenicity was confirmed by Koch’s postulates. This is the first report of A. alternata on B. myrtifolia that is a possible cause of leaf discolouration in B. myrtifolia.

Bio-Based and Biodegradable Plastics for Use in Crop Production

The production and management of crops uses plastics for many applications (e.g., low tunnels, high tunnels, greenhouses, mulching, silage bags, hay bales, pheromone traps, coatings of fertilizers or pesticides or hormones or seeds, and nursery pots and containers for growing transplants). All these applications have led some authors to adopt the term "plasticulture" when discussing the use of plastic materials in agriculture and related industries. Unfortunately, the sustainability of this use of plastics is low, and renewability and degradability have become key words in the debate over sustainable production and utilization of plastic. Recently, researchers and the plastics industry have made strong efforts (i) to identify new biopolymers and natural additives from renewable sources that can be used in plastics production and (ii) to enhance the degradability (biological or physical) of the new ecologically sustainable materials. In the present review, we describe the main research results, current applications, patents that have been applied for in the last two decades, and future perspectives on sustainable use of plastics to support crop production. The article presents some promising patents on bio-based and biodegradable plastics for use in crop production.

The use of controlled-release fertilizer in nursery pots for transplanting onion

The use of controlled-release fertilizer in nursery pots for transplanting onion

Compost and vermicompost as nursery pot components: effects on tomato plant growth and morphology

Post transplant success after nursery stage is strongly influenced by plant morphology. Cultural practices strongly shape plant morphology, and substrate choice is one of the most determining factors. Peat is the most often used amendment in commercial potting substrates, involving the exploitation of non-renewable resources and the degradation of highly valuable peatland ecosystems and therefore alternative substrates are required. Here the feasibility of replacing peat by compost or vermicompost for the production of tomato plants in nurseries was investigated through the study of the effect of increasing proportions of these substrates (0%, 10%, 20%, 50%, 75% and 100%) in target plant growth and morphological features, indicators of adequate post-transplant growth and yield. Compost and vermicompost showed to be adequate substrates for tomato plant growth. Total replacement of peat by vermicompost was possible while doses of compost higher than 50% caused plant mortality. Low doses of compost (10 and 20%) and high doses of vermicompost produced significant increases in aerial and root biomass of the tomato plants. In addition these treatments improved significantly plant morphology (higher number of leaves and leaf area, and increased root volume and branching). The use of compost and vermicompost constitute an attractive alternative to the use of peat in plant nurseries due to the environmental benefits involved but also due to the observed improvement in plant quality.

EFFECTS OF TYPE OF PLUG AND THE GROWING MEDIA ON EVAPOTRANSPIRATION AND GROWTH OF POTTED CARNATIONS

Plugs have a reduced rooting volume and consequently the key issue is to obtain an adequate water holding capacity. Hydrogels have demonstrated their potential to increase water retention in the medium. The physical properties of different growing media determine the availability of water which is a potential problem for the proper irrigation management in nursery pot production. This study evaluates the effects of using hydrogel added plugs and of two growing media on the evapotranspiration (ETp) and growth of potted Dianthus caryophyllus cv. 'Mondriaan'. Plugs were grown in two different substrate mixtures: peat moss and coconut fiber. Plugs with or without the addition of hydrogel (12 g L -1 ) were used. At the end of the cultivation cycle the plants growing from hydrogel added plugs and then cultivated in peat moss provided the highest fresh and dry weight, and the highest number of shoots and flowers per plant. The chlorophyll content of leaves was also higher when the plants were cultivated in peat moss. The water supplied to the peat moss grown plants was 13% higher than that needed by the plants grown in coconut fiber. The use of hydrogel-amended plugs did not significantly affect the water balance at the end of the cultivation cycle. Plant transpiration was significantly higher in peat moss compared to coconut fiber, probably due to the higher water holding capacity of the former. During the drought period imposed for five days at the end of the growing period, water was lost most rapidly from the peat moss during the first two days, while in the following days dehydration was more pronounced in the pots filled with coconut fiber.

Feasibility of creating compression‐molded biocomposite boards from berry fruit pomaces

AbstractIn this study, we investigated the feasibility of creating biocomposite boards from berry fruit pomaces on the basis of a crosslinking mechanism. Blueberry, cranberry, and wine grape pomaces were ground, dried, and mixed with soy flour (SF) or pectin and xanthan gum mixture at a ratio of 1 : 1 and with the addition of 15% glycerol (w/w of pomace and SF). Blueberry pomace (BP) was also blended with NaOH‐modified soy flour (MSF) at pomace/MSF ratios of 1 : 1, 4 : 1, and 9 : 1 and with 5, 10, or 15% glycerol. The mixtures were compression‐molded at 130–140°C into biocomposite boards to evaluate their mechanical and thermal properties, water absorption and solubility, and microstructure. Among the three pomaces, the BP board was the stiffest, whereas the wine grape pomace board was the most flexible. The breaking strength and modulus of elasticity of the BP/MSF boards increased with increasing MSF concentration but decreased with increased glycerol concentration. Mixing the pomace and glycerol into SF shifted the endothermic peaks and initial degradation to lower temperatures compared to that of SF alone. Increasing the glycerol concentration decreased the water absorption but increased the water solubility of the BP/MSF board. The pomace/MSF ratio in the board did not affect (P > 0.05) the water absorption, but the water solubility increased with increasing pomace concentration. Glycerol addition in the BP/MSF board smoothed the fracture surface, as shown by scanning electron microscopy images. This study may provide an approach to reducing fruit pomace disposal through the development of new value‐added biodegradable products for industrial applications, such as nursery pots and egg cartons. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Disease Risk of Potting Media Infested with Phytophthora ramorum Under Nursery Conditions.

Phytophthora ramorum has been found in potting media of containerized plants; however, the role of infested media on disease development under nursery conditions is unknown. This study assesses pathogen survival, sporulation, and infectivity to rhododendron plants in nursery pots with infected leaf litter that were maintained under greenhouse and field conditions. The influence of environmental conditions and irrigation method on disease incidence was also assessed. Infected leaf disks were buried below the soil surface of potted rhododendrons and retrieved at approximately 10-week intervals for up to 66 weeks. Pathogen survival was assessed by either isolation or induction of sporulation in water over three experimental periods. P. ramorum was recovered from infected leaf disks incubated in planted pots for longer than 1 year. Chlamydospores and sporangia formed on hydrated leaf disks but relative production of each spore type varied with the duration of incubation in soil. Root infections were detected after 40 weeks in infested soil. Foliar infections developed on lower leaves but only after spring rain events. Sprinkler irrigation promoted the development of foliar infections; no disease incidence was observed in drip-irrigated plants unless foliage was in direct contact with infested soil. Management implications are discussed.

Macro, minor and toxic elemental uptake and distribution in Hypoxis hemerocallidea, “the African Potato”—an edible medicinal plant

The elemental uptake and distribution, in various parts of the admired herbal plant, Hypoxis hemerocallidea, the ‘African potato’ and its ability to accumulate elements in response to the growth soil quality are investigated. The total and exchangeable concentrations of twelve elements in the growth soils and their distribution in the roots, potato bulb and leaves of the plants grown under four different settings were compared. The typical concentrations of the twelve selected elements, in the bulb and leaves of the plant grown in a nursery pot (site 2) were (in μ g g−1dry weight) Ca (8430 and 27075), Mg (2113 and 1566), Fe (66 and 150), Al (10 and 368), Zn (105 and 6.1), Mn (42 and 51), Cu (7.2 and 20.8), Ba (0.23 and 4.44), Co (0.20 and 0.42), As (2.05 and 24.56), Hg (0.92 and 1.82) and Cr (0.13 and 0.33). Except for Ca, Mg, Zn and Mn, the exchangeable cation concentrations in all the growth soils were low. Ca, Mg, Mn, Zn and As had bioaccumulation factors > 1. Fe, Al and Co concentrations were high in the roots with little in the rest of the plant. High concentration of arsenic (≈ 13 μ g g−1 dry weight) with bioaccumulation factors of 7 and 20 were observed in the roots and leaves of the plant respectively (site 2), but the concentration of mercury in bulb was very low (0.92 μ g g−1 dry weight).

DIFERENTES MISTURAS DE SUBSTRATOS NA FORMAÇÃO DE MUDAS DE PESSEGUEIRO, EM EMBALAGEM

No Brasil, a comercialização de mudas de pessegueiro (Prunus persica (L.) Batsch), em sua grande maioria, é feita através de raiz nua. Entretanto, uma alternativa tecnológica para o plantio em diferentes épocas é a produção de mudas em embalagens. O objetivo do presente trabalho foi avaliar a influência de diferentes substratos no desenvolvimento de porta-enxertos de pessegueiro e da cultivar Maciel produzidas em embalagens. Os substratos utilizados foram às combinações de Plantmax® + húmus + areia, Plantmax® + húmus, Plantmax® + húmus + casca de arroz carbonizada. A germinação das sementes foi em placas de Petri, tratadas com o fitorregulador Pro-Gibb® (GA3) na concentração de 200 mg L-1, durante 16 horas. As variáveis analisadas foram diâmetro do tronco, altura de planta, volume de copa e massa seca da planta. Até o período de enxertia (180 dias após o início da germinação), observou-se maior diâmetro de tronco na cv. Okinawa com substrato Plantmax®HT + húmus + casca de arroz carbonizada (5,9 mm) e Plantmax®HT + húmus + areia (5,8 mm), e em Aldrighi com os substratos Plantmax®HT + húmus + casca de arroz carbonizada (5,5 mm) e Plantmax® HT + húmus (5,4 mm). Dentre os porta-enxertos avaliados, a maior altura foi 46,6 cm no substrato Plantmax®HT + húmus, na cv Capdeboscq. Os maiores valores de massa seca foram observados nas plantas cultivadas no substrato Plantmax® HT + húmus. Após enxertia houve maior diâmetro de tronco no substrato Plantmax® HT + húmus (7,6 mm). Não houve influência significativa dos diferentes substratos no volume de copa e na altura das mudas enxertadas.

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Abstracts of Nippon Dojo-Hiryogaku Zasshi

A Single Basal Application of Total Nitrogen in Nursery Pot with Controlled Ability Fertilizers in Tomato Cultivation

A Single Basal Application of Total Nitrogen in Nursery Pot with Controlled Ability Fertilizers in Tomato Cultivation

First Report of Infection of Maiden-Hair Fern (Adiantum jordanii and A. aleuticum) by Phytophthora ramorum in California.

During July 2005, Phytophthora ramorum S. Werres & A.W.A.M. de Cock was isolated from nine native Adiantum jordanii plants growing at two forest sites (Samuel P. Taylor State Park, Marin County and Peachland Road, Mendocino County) and from seven A. aleuticum plants at one forest site (Peachland Road) in California. At both locations, symptomatic plants were distributed close to rivers and roads and in association with infected bay laurel trees (Umbellularia californica), toyon (Heteromeles arbutifolia), and tanoaks (Lithocarpus densiflorus). Symptomatic leaflets showed brown spots that sometimes coalesced, killing entire leaves, but the disease did not appear to be fatal to the ferns. Necrotic tissues were plated on PARP and maintained in the dark at 18°C for 1 to 2 weeks. Isolates were identified as P. ramorum on the basis of colony morphology, the presence of chlamydospores and caducous, semipapillate sporangia, and the internal transcribed spacer (ITS) rDNA sequences (1,2). The P. ramorum isolates, Pr-419 from A. jordanii and Pr-422 from A. aleuticum, have been deposited in the American Type Culture Collection (ATCC MYA-3677 and MYA-3679, respectively) and a region of the ITS rDNA sequence deposited in the NCBI database (GenBank Accession No. DQ173082 and DQ219821, respectively). To test the pathogenicity, the tips of freshly detached leaves of A. jordanii and A. aleuticum were dipped into a solution of 1 × 103 zoospores per ml of Pr-419 and Pr-422 for 1 min. The wounded end of the leaves was not exposed to the inoculum. The zoospores were produced by flooding agar disks (1 cm in diameter) from the margin of 8- to 14-day-old colonies growing on V8 juice agar with sterile deionized water. After 3 days of incubation at 20°C in the dark, zoospore release was induced by placing dishes at 4°C for 20 min and then at room temperature for 60 min. For each Adiantum species and P. ramorum isolate, 15 leaves collected from five potted nursery plants were tested. Control leaves were dipped in sterile deionized water. Leaves were maintained in a moist chamber at 19°C with 13 h of natural light for 9 days. Brown lesions similar to those seen in the forest developed on approximately 60 and 33% of the A. jordanii and A. aleuticum leaves, respectively, inoculated with Pr-419 and on approximately 73 and 40% of the leaves inoculated with Pr-422. Under these experimental conditions, A. aleuticum appeared to be slightly more susceptible than the A. jordanii, with a necrotic leaf area of approximately 38% compared with 20%. The pathogen was reisolated on PARP after surface sterilization from all symptomatic leaves. Control leaves did not develop symptoms and P. ramorum was not recovered. A. jordanii and A. aleuticum have already been listed as associated hosts for P. ramorum on the APHIS (USDA Animal and Plant Health Inspection Service) website ( http://www.aphis.usda.gov/ ). To our knowledge, this is the first report of ferns as natural hosts of P. ramorum.

Morphological and molecular characterisation of Puccinia lagenophorae, now present in central North America

AbstractIn June 2004, a rust fungus not previously reported for Oklahoma was found occurring naturally on the weed, common groundsel, Senecio vulgaris, in pots in a commercial container nursery in northeastern Oklahoma. Host symptoms and morphology of teliospores and aeciospores of the fungus were consistent with those of Puccinia lagenophorae, a recent introduction into North America that has, as yet, been reported only on the East and West Coasts of the USA. This is the first report of the rust in central regions of North America. The rust is believed to be native to Australia and New Zealand and subsequently reported in most continents on numerous species and genera of the Asteraceae. Some authors in Europe consider the rust on Bellis as different from the one on Senecio, naming it Puccinia distincta. Our ITS1‐5.8S‐ITS2 ribosomal DNA sequence data, however, show homology with P. distincta sequences from Europe, indicating there is only one morphologically‐variable polyphagous species. Presumably, the rust was introduced into Oklahoma on infected plants from the West Coast of the USA, the source of most plant material in the commercial nursery where it was found. The rust is potentially important on several ornamental Asteraceae in North America as it has become in Europe, where it spreads rapidly throughout that continent following its introduction there in the early 1960s.

Response of herbage regrowth and water‐soluble carbohydrate concentration of ryegrass species to defoliation practices when grown in a Mediterranean environment

AbstractThree experiments were conducted to determine the association between leaf number per tiller at defoliation, water‐soluble carbohydrate (WSC) concentration and herbage mass of juvenile ryegrass plants when grown in a Mediterranean environment. Seedlings of ryegrass were grown in nursery pots arranged side‐by‐side and located outside in the open‐air to simulate a mini‐sward in Experiments 1 and 2, and a mixture of annual ryegrass and subterranean clover (Trifolium subterraneum L.) was grown in a small plot field study in Experiment 3. Swards were defoliated mechanically with the onset of defoliation commencing within 28 d of germination. Frequency of defoliation ranged from one to nine leaves per tiller, whilst defoliation height ranged from 30 mm of pseudostem height that removed all leaf laminae in Experiment 1, to 50 mm of pseudostem height with some leaf laminae remaining post‐defoliation in Experiments 2 and 3.A positive relationship between herbage mass of ryegrass, WSC concentration and leaf number per tiller at defoliation was demonstrated in all experiments. In Experiment 1, the herbage mass of leaf, pseudostem and roots of tillers defoliated at one leaf per tiller was reduced to 0·10, 0·09 and 0·06 of those tillers defoliated less frequently at six leaves per tiller. However, the reduction in herbage mass from frequent defoliation was less severe in Experiment 2 and coincided with a 0·20 reduction in WSC concentration of pseudostem compared with 0·80 measured during Experiment 1. In Experiment 3, the highest harvested herbage mass of ryegrass occurred when defoliation was nine leaves per tiller. Although the harvested herbage from this sward contained senescent herbage, the in vitro dry‐matter digestibility of the harvested herbage did not differ significantly compared with the remaining treatments that had been defoliated more frequently.Leaf numbers of newly germinated ryegrass tillers in a Mediterranean environment were positively associated with WSC concentration of pseudostem and herbage mass. A minimum period of two to three leaf appearances was required to restore WSC concentrations to levels measured prior to defoliation thereby avoiding a significant reduction in herbage mass. However, maximum herbage mass of a mixed sward containing ryegrass and subterranean clover was achieved when defoliation was delayed to nine leaves per tiller.

Mouse-ear of Pecan: A Nickel Deficiency

Mouse-ear (ME) is a potentially severe anomalous growth disorder affecting pecan [Carya illinoinensis (Wangenh.) K. Koch] trees. It is especially severe in second generation sites throughout much of the Gulf Coast Coastal Plain of the southeastern U.S., but can also occur in potted nursery trees. Orchard and greenhouse studies on trees treated with either Cu or Ni indicated that foliar applied Ni corrects ME. ME symptoms were prevented, in both orchard and greenhouse trees, by a single mid-October foliar spray of Ni (nickel sulfate), whereas nontreated control trees exhibited severe ME. Similarly, post budbreak spring spray applications of Ni to foliage of shoots of orchard trees exhibiting severe ME prevented ME symptoms on subsequent growth, but did not correct morphological distortions of foliage developed before Ni treatment. Foliar application of Cu in mid-October to greenhouse seedling trees increased ME severity the following spring. Post budbreak application of Ni to these Cu treated MEed seedling trees prevented ME symptoms in post Ni application growth, but did not alter morphology of foliage exhibiting ME before Ni treatment. Thus, high leaf Cu concentrations appear to be capable of disrupting Ni dependent physiological processes. Foliar application of Ni to ME prone trees in mid-October or soon after budbreak, is an effective means of preventing or minimizing ME. These studies indicate that ME in pecan is due to a Ni deficiency at budbreak. It also supports the role of Ni as an essential plant nutrient element.