Lesion development and conidial production of &lt;i&gt;Neonectria ditissima &lt;/i&gt;on apple trees in four New Zealand regions

Scheper, R.W.A.; Vorster, L. F.; Turner, Lauren; Campbell, Rebecca E.; Colhoun, K.; McArley, Danielle; Murti, Rosalind; Hodson, A.; Beresford, R.; Stock, Maryam; Fisher, B.M.; Hedderley, Duncan I.; Walter, Monika

doi:10.30843/nzpp.2019.72.302

Cited by 8 publications

(10 citation statements)

References 13 publications

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“…Usually, a longer duration of a wet period leads to a higher incidence of infection. Infection occurs over a wide temperature range (Kennel 1963, Wilson 1966, Dubin 1975 with temperature being the main driver for symptom development and rainfall frequency for conidial production (Scheper et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Does apple canker develop independently on leaf scars of a single apple shoot?

Olivieri

Gange

et al. 2021

NZPP

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European apple canker, caused by Neonectria ditissima, causes serious damage to apple trees, particularly young trees. Canker management is difficult because of the limited availability of effective fungicides, the long latency period, inoculum abundance and host resistance in commercial cultivars as well as the need for costly manual pruning interventions. To understand disease aggregation for more effective pruning management, we assessed whether canker infection and subsequent lesion development on leaf scars are independent from each other on the same shoot. Four inoculation experiments were conducted: one in glasshouse, and three in orchards. On each shoot, 10 consecutive leaf scars were inoculated and assessed for visible cankers over time in situ. Number of cankers developed per shoot as well as spatial distribution of these cankers within a shoot was statistically analysed. Most data of the number of visible canker lesions on a single shoot failed to fit binomial distributions (indicator for independence) and were fitted much better by beta binomial distributions. In a number of cases (4–20%), there appeared to be positive association between lesion development on neighbouring leaf scars. However, in one experiment where laboratory incubation and isolation of N. ditissima from inoculated but asymptomatic leaf scars (after eight months’ field incubation) were used the results suggested independence of canker development on a single shoot. We conclude that apparent aggregation of canker lesions on individual shoots is likely to originate from host responses. Such aggregation of canker lesions on individual shoots should be taken into consideration for field disease assessment and management.

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Section: Introductionmentioning

confidence: 99%

Does apple canker develop independently on leaf scars of a single apple shoot?

Olivieri

Gange

et al. 2021

NZPP

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“…This, however, was typical for the 2015 season (Dryden et al 2016). Temperature was found to be the main driver for symptom development with rainfall frequency determining spore production potential (Beresford & Kim 2011;Scheper et al 2019). It is unlikely, that leaf-scar…”

Section: Discussionmentioning

confidence: 98%

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

Walter

Manktelow

Berre³

et al. 2019

NZPP

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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.

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“…'Pinova' 2013, this is unlikely to have had a decisive effect because even the lower concentration, at 5×10 4 conidia mL -1 , was well within the effective range at least for wound infections of N. ditissima leading to canker (Walter et al 2016). Differences in symptom expression between years may arise even after standardised inoculation, and these have been explained by differences in weather conditions, notably temperature (Scheper et al 2019). However, the likeliest explanation is based on the assumption that the susceptibility of cultivars to flower infections reflects that of wounds in the bark, which is notoriously high in cv.…”

Section: Discussionmentioning

confidence: 99%

Apple blossom-end rot due to Neonectria ditissima is initiated by infections at full flowering and incipient petal fall

Holthusen

Weber

2021

NZPP

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Neonectria ditissima is a major cause of blossom-end rot (eye rot, calyx-end rot) as a pre-harvest fruit rot of apple in Northwestern Europe. Artificial inoculation of trees was undertaken at close intervals under natural conditions during flowering in order to obtain a higher-resolution definition of the most susceptible phenological stage of apple for blossom-end rot infections by N. ditissima. Similar trials were conducted for another blossom-end rot fungus, Botrytis pseudocinerea. Results for N. ditissima showed full bloom to be the most susceptible stage for infection in cultivar ‘Pinova’, whereas with cultivar ‘Nicoter’ the highest infection rates were obtained at full bloom to petal fall, reflecting temporal differences in flower development between one-year-old and older wood. Few infections were observed by inoculation at the beginning of flowering or about one week after petal fall when no petals were left on the flowers, and the fruit knots were enlarging. This finding shortens the time-span for infections as compared to previous knowledge. Floral inoculations with conidia of B. pseudocinerea were unsuccessful. Options to control blossom-end rot in integrated pest management include a timing of scab or powdery mildew fungicide sprays to full bloom, and canker pruning just ahead of flowering in orchards strongly affected by N. ditissima.

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Lesion development and conidial production of <i>Neonectria ditissima </i>on apple trees in four New Zealand regions

Cited by 8 publications

References 13 publications

Does apple canker develop independently on leaf scars of a single apple shoot?

Does apple canker develop independently on leaf scars of a single apple shoot?

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

Apple blossom-end rot due to Neonectria ditissima is initiated by infections at full flowering and incipient petal fall

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