It disappoints me to see this kind of article so uncritically received here. This is on par with, say, a "scientific" article claiming that the lack of a changi

It disappoints me to see this kind of article so uncritically received here. This is on par with, say, a "scientific" article claiming that the lack of a changing trend in the date of the Canadian wheat crop harvest is indisputable evidence that climate change does not exist. As well as the possible influences you list there are many more - changes in local water or air chemical content, changes in cultivation techniques, planting arrangements, chemical treatments (fertilizer, pesticide, herbicide, etc), changes in the biology of the plant due to natural or artificial selection, changes in pests or other influences of introduced or changing balances of plants/animals/fungi/bacteria. And surely many more I haven't listed. Come on HN, I've seen you fiercely argue the finer points of computer science, rocketry, quantum mechanics and pounce on any slight inconsistency or omission! You don't need to throw rational thinking out the window when you read something that seems like it is "on your side". There exists far stronger evidence of climate change than this.