Archaeologists love to comb through waste dumps. No evidence of wheat or apples there.

Iceland has a milder climate, and much stronger trade links, than Greenland. They have never grown wheat there (including today). As an aside, Iceland has a variety of trees to chose from that will grow well or marginally.

So far (I will confirm) only Siberian larch has been planted in Greenland.
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[edit] A number of tree species have been planted in Greenland (Scotch Pine 100+ years ago, today 2.5 to 3 m tall). Several species survive but only Siberian larch can be said to grow. And only along the interior Fjords of the south (where the Eastern Settlement was).

The Western Settlement was treeless (and charcoal less), but the Eastern Settlement had limited short willows & birches along the interior fjords, but a very limited resource that would have been pressured by sheep farming. And iron could well have been an essential export from the Newfoundland Settlement. Unfortunately, access to Newfoundland required trees to make ships from.

[I might mention that apple orchards and sheep farming are incompatible without extensive fences, the sheep will rapidly kill the trees w/o high and extensive fences (Icelanders traditionally free range their sheep, fences were impractical). Fruit trees have sugar in their bark are are "sheep candy" AFAIK. Another strike against Greenlandic apple trees.]

Throstur also pointed out that the concept of sustainable development came from forestry. A 1713 book on silvaculture Economics in German was the first mention, he said the name of the author but I forgot[/edit]

There is no other historic record of wheat or apples, both of which would have been trade goods with Iceland, which had neither.

Throstur's theory of collapse of Greenland and not Iceland is that Iceland had small trees large enough to make charcoal, Greenland did not. Charcoal is needed to make iron (note that Viking Settlement in Newfoundland (perhaps 150 people max) had an iron foundry). Iron is needed to harvest hay. Hay is needed to keep sheep & cattle over winter. Once Greenland's declining trade links deprived them of iron, starvation was just a matter of time.

Such a theory argues against apple trees.

Greenland Vikings were never a large colony. Even much larger, and closer Iceland would go over a year without a trade vessel at various times in their history. (Although such years were rare and were complained of in the chronicles of the time).

Alan