They also passed low stone walls in the fields, Gordon. Take a look at this fragment and you will understand why: “In front of the house where we lived the mountain went down steeply to the little plain along the lake and we sat on the porch of the house in the sun and saw the winding of the road down the mountain-side and the terraced vineyards on the side of the lower mountain, the vines all dead now for the winter and the fields divided by stone walls, and below the vineyards the houses of the town on the narrow plain along the lake shore. There was an island with two trees on the lake and the trees looked like the double sails of a fishing boat. The mountains were sharp and steep on the other side of the lake and down at the endo of the lake was the plain of the Rhone Valley flat between the two ranges of mountains; and up the valley where the mountains cut it off was the Dent du Midi. It was a high snowy mountain and it dominated the valley but it was so far away that it did not make a shadow.” So the fields were divided by stone walls in that region.

First of all 'candelabraed pear trees' is an expression that very few people would use. However think about a candelabrum with many arms to hold candles. Then imagine that a pear tree has its branches attached to a wall so that they grow like the arms of a candelabrum. Why would someone want to do that? No idea. However it seems that some people do that with pear trees. Make a search on google for 'candelabra pear tree' and you'll see some images of what I mean. From the pictures you will see that you do not need a high wall for a cadelabraed pear tree. I don't have a clue why I know this. I probably saw them in Italy somewhere. When I read your sentence I understand, 'we passed stone farmhouses with (some) pear trees candelabraed against their south walls (of the farmhouses) and (some pear trees candelabraed against) low stone walls in the fields.' The reason why I do not think that it's the other option (that is, we passed stone farmhouses with pear trees candelabraed against their south walls and we passed low stone walls in the fields) is mostly stylistic. If that was the intended meaning, IMMO the sentence would possibly have been written as, 'we passed low stone walls in the fields and stone farmhouses with pear trees candelabraed against their south walls.' That is because 'low stone walls in the fields' is far shorter than 'stone farmhouses with pear trees candelabraed against their south walls.'

It isn't possible to tell from the grammar. But it doesn't matter either. The general meaning doesn't change whichever way you interpret it.