Botanical classification: Malus pumila Mill.

Variety denomination: ‘M116’ (nonpatented).

In 1962 and 1964, two rootstocks of apple (Malus pumila Mill.), ‘Malling-Merton 106’ (nonpatented) (Seed parent) and ‘Malling 27’ (nonpatented) (pollen parent), both not patented, were crossed in a cultivated area of West Malling, Kent, England. These crosses produced 56 (AR10 series) and 59 (AR86 series) seedlings, respectively. After the completion of preliminary screening tests, eight seedlings from the AR10 series and seven from the AR86 series were selected and propagated in 1973 for further evaluation. The vigour of each selection, when grown as hard-pruned hedges in the nursery, was recorded between 1979 and 1983. The potential vigour of the selections when used as rootstocks was estimated from measurements of the percentage of bark tissue in young roots, using techniques first described by Beakbane and Thompson (1947) and later modified by Werts et al. (1976). This percentage root bark was measured a number of times between 1974 and 1980 on root samples from all of the 15 selections. One of the seedlings, ‘AR 86-1-25’ (nonpatented) had 52% rootbark.

The ability of these selections to root and establish from hardwood cuttings was assessed in a minimum of six separate propagation trials conducted during 10 years. In each test the rooting and subsequent establishment of hardwood cuttings of each selection were evaluated using techniques developed at East Malling Research Station (Howard, 1971). For ‘AR86-1-25’ (nonpatented), 63% of cuttings rooted and established in the field.

The incidence of mildew (Podosphaera leucotricha) was observed over several years on most of the selections growing as hedges and receiving the standard East Malling Research Station nursery spray programme for pests and diseases. ‘AR86-1-25’ (nonpatented) was found to be relatively resistant. The selections were scored for resistance to woolly apple aphid (Eriosoma lanigerum) in tests on small potted specimens grown under glass (Lyth and Watkins, 1981). The rating of ‘AR86-1-25’ (nonpatented) was inconclusive but it has since been recorded as resistant. The selections were also scored for resistance to collar-rot (Phytophthora cactorum). ‘AR86-1-25’ (nonpatented) was rated as fairly resistant. Finally, the field resistance of many of the selections to specific apple replant disease (SARD) was evaluated (Oehl and Jackson, 1980). ‘AR86-1-25’ (nonpatented) was considered resistant.

‘AR86-1-25’ (nonpatented) was first asexually reproduced in 1973 in East Malling, Kent, England by hardwood cuttings and subsequent generations have been true to phenotype.

Rooted cuttings of ‘AR86-1-25’ (nonpatented) were lined out and budded with ‘Cox's Orange Pippin’ (nonpatented) in 1974. The maiden trees were planted at 3 m×5 m in a replicated design with eight randomised blocks in February 1976 at East Malling. ‘Malling 9 (nonpatented, ‘Malling 26’ (nonpatented) and ‘Malling-Merton 106’ (nonpatented) were also lined out and budded with ‘Cox's Orange Pippin’ (nonpatented) in 1974 and planted in the orchard for comparison. A weed-free strip 2 meters wide was maintained beneath the tree rows. The trees were minimally pruned and trained as open centre bushes. Shoot growth, floral buds, fruit set and yields were recorded on various occasions and the weight of the above ground portion of each tree recorded at grubbing.

‘AR86-1-25’ (nonpatented) produced trees of similar or slightly smaller size than those on ‘Malling-Merton 106’ (nonpatented) and bore abundant flowers which set fruit efficiently. Yield and fruit grade-out for ‘Cox's Orange Pippin’ (nonpatented) on ‘AR86-1-25’ (nonpatented) were better than for ‘Malling-Merton 106’ (nonpatented). The 5 year cumulative total yields of ‘Cox's Orange Pippin’ (nonpatented) were higher on ‘AR86-1-25’ (nonpatented) than on MM.106 (82 kg compared to 68 kg) ‘AR86-1-25’ (nonpatented) exhibits improved resistance to collar rot and specific apple replant disease than ‘Malling-Merton 106’ (nonpatented). From the trial evidence, it was concluded that ‘AR86-1-25’ (nonpatented) could provide an improved rootstock over ‘Malling-Merton 106’ (nonpatented).

In a trial conducted in Hawkes Bay, New Zealand, the number of flower clusters per unit tree size of Royal ‘Gala’ (nonpatented) has been similar for trees on M.116 and MM.106 (7-8 spur and terminal clusters per unit trunk cross sectional area). However, in a trial conducted in Central Otago, New Zealand, spur abundance was slightly lower for trees on M.116 compared with trees on MM.106. Cumulative yields and yield efficiencies were similar for Royal ‘Gala’ (nonpatented) trees on ‘M116’ (nonpatented) and MM.106 in the Hawkes Bay, New Zealand trial.

‘M116’ (nonpatented) is different from the pollen parent Malling 27 in that ‘M116’ (nonpatented) has larger flowers and a green-brown bark 199A/152A. The bark of ‘Malling 27’ (nonpatented) is brown 200C.

On the basis of the testing carried out in the UK and New Zealand it was considered that ‘AR86-1-25’ (nonpatented) was a commercially useful rootstock and the Policy Group of the HRI Apple and Pear Breeding Club decided to release it under the name M116. ‘M116’ nonpatented) has not been observed under all possible environmental conditions and its phenotype may vary significantly with variations in environment such as temperature, light intensity, and day length, without any variation in genotype. However, the following unique combination of characteristics relating to the use of ‘M116’ (nonpatented) as a rootstock for apple varieties, distinguish ‘M116’ (nonpatented) from all other apple varieties known to the inventor.

The following is a detailed botanical description of the new cultivar of Malus pumila Mill. named ‘M116’. Observations, measurements, values, and comparisons were collected in West Malling, Kent, England from a 9 year old tree grown in full sun and on 1 year old shoots.

Terminology used is in accordance with Michael Hickey and Clive King: The Cambridge Illustrated Glossary of Botanical Terms, 2000 Cambridge University Press.

‘M116’ has not been observed under all possible environmental conditions. The phenotype may vary with variations in the environment such as temperature and light level, without, however, any variance in genotype. Color references are made to The Royal Horticultural Society Colour Chart except where general terms of ordinary dictionary significance are used.