1. Does anybody know what is the actual frost tolerance of yacón plant? By description this plant is not hardy. But what kind of frost will actually damage it? We have had abnormally cold July (4...5 degrees colder, than average) this year. Tonight and the night before it the air temperature dropped to +4 and on the ground there was shortly even a light frost, because of clear night sky, near full moon and the cyclone, that brought cold air from the Arctic. Both nights I covered my yacóns, that are planted into 90 L plastic bags in my garden and have grown ca 40 cm high for now, with a floating row cover. Yesterday morning I checked those plants for damages, some leaves look like slightly wilted, but in the afternoon they were ok again. Should I be careful because of such light frost (temperature drops to zero or maybe even to -1ºC for maximum an hour) or those plants should withstand short light frost even without a floating cover? Usually July is the only month, that has no frosts here and gardeners can sleep in peace. But it seems, that as global climate is warming, our July is not quaranteed to remain frost free any more. 2. I have heard, that yacón is virtually a pest free vegetable. But I am finding more and more pests that are interested in my yacóns. Most agressive are snails and small green caterpillars, who are chewing holes into the leaves. It seems, that I found a way to prevent snails from attacking my yacóns, but those green larvae appear to continue their attack. Are those Silver Y moth (Autographa gamma) caterpillars (see the attached photo)?
Now I can answer to my first question by myself. We got officially +1.4°C lowest air temperature last night (-0.3°C on the ground level), but this weather station is more than 8 km away, much closer to the sea than my garden. My local thermometer got -1°C for the air temperature and surface measurements with an IR thermometer gave down to -7°C for the ground temperature. All the grass was in hoarfrost and the metal gate of my garden was covered with thick layer of ice (it was raining yesterday several times until the evening). Yesterday evening, after seeing the weather forecast, I transported one yacón container into my 2 layer melon tent for frost protection (but damaged the plant seriously by transportation and decided not to move the rest) and put single layer floating row cover on top of my other yacóns. The frost has catched some branches, that left uncovered (yacóns are very lush and wide), and tops that were touching the row cover. So yacón is really very tender to the frost. Ocas, for instance, performed much better, without any visible damages under old holey single layer floating row cover. Still have no idea about the pest, but it seems, that total damage from all the pests is much smaller than damage from the short hail 5 days ago.
