Can phosphorous acid be used to control Neonectria ditissima in New Zealand grown apples?

European canker, Neonectria ditissima, is a worldwide apple tree disease killing shoots, branches and trees, and treatment with phosphorous acid is a possible control option. The effect of six postharvest phosphorous acid (PA) treatments on fruit residues the following season was studied in Tasman on two trial sites growing ‘Scifresh’ or ‘Scilate’ apple trees. Spray treatments consisted of number (0–3) and timing (early, mid and/or late) of PA applications. Additionally, leaf-scar wounds were artificially inoculated with N. ditissima spores at the ‘Scilate’ site on 1 and 8 June 2017 to determine disease control. Symptom expression was checked regularly between October 2017 and February 2018. None of the treatments caused a statistically significant reduction in the incidence of canker development compared with the control. Two or more PA applications resulted in PA residues in fruit, at harvest, the following season. Higher PA residues were found in fruit following early applications than with late applications. More applications of PA resulted in higher residues. This finding has important implications for exporting fruit to markets that have no tolerance for PA residues.

How much captan is required for wound protection of Neonectria ditissima conidial infection in apple?

Captan (a trichloromethyl sulfenyl fungicide) is commonly used for control of Neonectria ditissima in apple. In New Zealand, picking and leaf scars are the main source of new infections. The captan concentrations required for wound protection of leaf scars, picking and rasp wounds was determined in planta. Fresh wounds, inoculated with N. ditissima, were sprayed with captan using a motorised knapsack (leaf scars) or hand-held spray bottles targeting the wound area (picking and rasp wounds). Captan concentrations ranged from 0 to 400% field rate (100% = 2 kg captan/ha). Wounds were sampled pre- and post-captan application for residue analyses and the remainder assessed regularly in the field for disease expression. Disease development decreased as captan concentrations increased. Approximately 2 μg captan/scar (100% field rate) was required to protect leaf scars. Four times the field rate of captan was needed for a 55 and 70% disease reduction on picking and rasp wounds, respectively. Label-rate applications of captan controlled low incidence of N. ditissima leaf-scar infections in the field in autumn, but disease control of picking scars and other large wounds might be difficult to achieve.

Postharvest foliar nitrogen applications increase Neonectria ditissima leaf scar infection in apple trees

Postharvest foliar nitrogen (urea) is often applied to apple leaves immediately after picking for bud fertilising and/or during leaf fall for Venturia inaequalis control During 20132016 ethylene diamine tetraacetic acid copper (EDTACu to enhance leaf abscission) urea calcium nitrate and BudWiser foliar treatments were applied alone or in combination to determine their effects on leaf scar infection by Neonectria ditissima in Braeburn (201314) Scifresh and Royal Gala (201516) orchards In 201314 leaf scar infection increased sixfold when 5 urea was added to EDTACu and sprayed at the onset of leaf fall In 201516 up to a ninefold increase in leaf scar infections was observed The timing of application was more important than the amount or form of nitrogen used As a result of this research the use of ureabased foliar nitrogen fertilisers for V inaequalis before leaf fall are not recommended and growers should consider all factors affecting Neonectria ditissima infections before applying nitrogen immediately after harvest

Seasonal wound presence and susceptibility to Neonectria ditissima infection in New Zealand apple trees

Leaf scar wounds are important sites for Neonectria ditissima infection of apple trees Monitoring leaf fall in Scilate/Envy and Braeburn trees to estimate leaf scar wound presence showed maximum leaf scar incidence occurred in June (early winter) Wounds detected in New Zealand apple orchards were bud scale scars fruit thinning and picking wounds leaf scars and pruning cuts Picking wounds are caused during harvest where the pedicel is detached from the shoot Susceptibility of these different types of wounds was determined using artificial inoculation of N ditissima conidia during the season Pruning cut wounds were the most susceptible followed by fruit picking and thinning wounds and the least susceptible were leaf scar wounds No infections were observed when bud scale wounds were inoculated There was no difference in wound susceptibility between cultivars but overall Scilate/Envy wounds developed more lesions than Braeburn wounds

Control of Neonectria ditissima with copper based products in New Zealand

New Zealand pipfruit crops require postharvest fungicides for control of European canker caused by Neonectria ditissima Fungicide efficacy trials to protect leaf scars from N ditissima infections were conducted during autumn 2013 and 2014 Disease control of artificially inoculated leaf scars was achieved by single applications of copper oxychloride and copper oxide but not copper hydroxide applied at 43 11 and 06 kg elemental copper/ ha respectively Control of leaf scar infections by copper oxide (065 and 095 kg elemental copper/ha) was similar to control by captan Leaf scars (010 days old) remained susceptible to infections up to 10 days after leaf fall; disease control was achieved by redistribution of copper and captan fungicides onto new leaf scars Disease control using copper oxide was consistent and similar to control using captan The copper product and concentration of elemental copper are important for successful control of leaf scar infections by N ditissima

Heterophyton, a new substitute name for Allophyton X.W. Wu (Pteridopsida)

The filicopsid pteridophyta genus Allophyton X.W. Wu (1982) was established for A. dengqenensis X.W. Wu collected in Badasongduo, Dingqing County of Xizang Province, China. It was listed in Index of generic names founded on Mesozoic-cenozoic specimens from China (Wu 1993: 498) and its taxonomic position is unsettled. Rhizomopteris Schimp. (1869: 699) differs from it in its fine and furcate stem, and bundle scar in leaf scar hippocrepiform, Caulopteris Lindl. & Hutton (1832: xlix) differs from it in its leaf scar regular spread, and bundle scar in leaf scar hippocrepiform. The materials of Allophyton were collected in Mesozoic Coal Series strata, coal-bearing strata that were regarded as Jurassic by Li (1955) and from late Triassic to early-middle Jurassic by Si & Zhou (1962).