Arcadia Update May14

Arcadia – May 2014 update (Photos to follow shortly)

All 9 seedlings of the 2013 Arcadia (Morfeo x Patriot) progeny survived last year’s growing season, though AR 3 lost its upper third to drought during a period of neglect, and all the trees were quite seriously affected by sooty mould towards the end of the summer.

Final heights ranged from 80cm (AR 1) to 46cm (AR 8). Mean height was 64.5cm.

The sequence of leaf colouring was observed in October 2013 (earliest to latest):

AR 7; AR 5; AR 4; AR 1; AR 6; AR 3, 8, & 9; AR 2.

The progeny over-wintered outside, and dates of budburst were as follows:

  • Feb 23           AR 2
  • Feb 27           AR 5
  • Mar 4            AR 3
  • Mar 7            AR 8, AR 9
  • Mar 11           AR 4
  • Mar 13          AR 7
  • Mar 16          AR 1
  • Mar 30         AR 6

A preliminary assessment of the plants was carried out on 20 May 2014. The criteria were adapted to bring out the strengths and weaknesses of this particular progeny; for example, foliage colour was given major importance because it is a marked weakness of some of these plants. “Leaf” refers to shape, size and arrangement within the spray. Scores for “shoot” penalised plants with markedly red shoots (atypical of native elm). Flush/fall scores were lower for abnormalities such as excessively early leafing and consequent frost risk.

 

  AR 1 AR 2 AR 3 AR 4 AR 5 AR 6 AR 7 AR 8 AR 9
Vigour(/20) 13 15 14 8 8 8 8 7 4
Colour(/20) 8 16 7 8 6 18 15 16 17
Form(/20) 16 14 13 10 8 14 11 7 5
Stability(/15) 12 11 13 10 5 12 9 10 9
Leaf(/15) 11 7 9 7 5 10 9 7 9
Shoot(/5) 5 4 4 3 2 5 4 3 3
Flush/fall(/5) 5 3 5 5 4 3 4 5 5
Total(/100) 70 70 65 51 38 70 60 55 52

AR 1, 2 and 6 tied in first place on 70% each. Individual photos and descriptions follow below. These are 3 markedly different but fairly attractive trees which seem worth taking forward to inoculation trials in the hope that they will show good resistance to DED. AR 3 and AR 7 will be inoculated in case they show exceptional resistance. The remaining clones have more than their fair share of faults, and are to be discarded.

AR 1 2014AR 1 made the strongest growth in 2013, and shows reasonable vigour so far this year. Diametric increment at the base is easily the best of the progeny. It is let down by a full measure of the glaucous down inherited through Morfeo from U. chenmoui. This is a shame, because it has good structure and form. Particularly interesting is the combination of few but strong side branches with the upright stem, and a fan of new leading shoots of which one seems able to exert apical dominance over the others. This is close to the growth habit of native elm, and is not seen in the other clones of this progeny which are either pyramidal or amorphous. Leaf shape is somewhat too small and lanceolate to be ideal, but the arrangement of leaves in the spray is attractive, the serration is interesting, and there is an elegant assortment of leaf sizes and direction. If AR 1 shows good resistance, it could ultimately be for crossing with a plant of better colour such as FL 493.

 

 

AR 2 2014AR 2 made slightly less growth than the mean in 2013, but is notably vigorous in 2014, growing some 2 cm a day. Its juvenile form is broadly herringbone with strong side-shoots. Leafing is comparatively sparse, though there are no blind buds. Appearance is quite strongly Asiatic. Leaf colour is good, but venation is too pronounced. One question is whether this clone will be able to support its rapid extension growth any better than Patriot, which it resembles. Another issue is its extremely early flushing (23 February in the admittedly very mild spring of 2014). Surprisingly it seems to hold its leaves longer than the other clones. One would have expected early flushing to be balanced by early fall. Vulnerability to slug and snail feeding is greater than in the rest of the progeny.

 

 

 

AR6 2014AR 6 is an elegant and obviously monopodial plant of excellent colour. Side shoots are horizontal and their extension growth is limited. It made strong growth in 2013 (72 cm), but is currently showing disappointingly little vigour. The clone leafed a full two weeks later than any other, so growth may perhaps accelerate later as well. Leaves are richly coloured with a touch of dark gloss, but are distinctly small and pointed; the overall impression is of delicacy. Stems show no red colouring at all. On balance this plant makes an impression closest to that of native elm, but if it passes the resistance tests it may ultimately be more suited to horticultural than landscape use.

 

Others

AR 3 has a statuesque quality and good vigour, but is badly let down by its colour. AR 7 is attractively rustic, but its current lack of vigour seems to consign it to the status of a by product.

Interim Conclusion

The Arcadia crossing clearly demonstrates that a hybrid progeny will not necessarily display characteristics expressed by the parent trees. All the 9 plants obtained have leaves smaller than either Morfeo or Patriot. The leaf outlines of some of them are found in neither of the parent clones, and Morfeo’s tendency to orbicular leaves has (unfortunately) found no expression in most of the offspring. 8 of the 9 plants seem more fully foliated than Morfeo or Patriot. The apparently low vigour of 6 of the 9 plants is surprising.

The crossing may perhaps be worth attempting again in the hope of obtaining a larger progeny which might include higher-scoring plants. Meanwhile the three best from 2013 – if they prove to be disease-resistant – will add diversity to the range of modern elm hybrids.