Tell your father to water the soil, not the plant, and that Tomatoes only need a good soaking weekly even in hot weather. Keep a keen eye on some of those spots: if they grow in size nip off all the affected leaves and consider spraying the remaining good foliage with copper sulfate solution or whatever organic spray you have at your disposal; or if the whole plant is affected pull the whole thing up. You can compost the affected parts, but do so under a layer of other material.
The mystery plant looks to me like Lily of the Valley -edit- definitely looks more like the False Hellebore.
Mike Gaughan wrote:Now the question is how to eradicate the fase hellebore? There are too many dogs and grandchildren running around the yard to have such a highly toxic plant present. The CT Horticultural Society's response is to apply 2,4-D. Thanks, but no thanks. Can't really do a kill mulch since they are spread throughout the yard. Hmmm.....
Depending on how many of them there are ... you could try salt solution on them. Just the leaves etc. We use either plain table salt sprinkled on the leaves of weeds or for bit ones salt solution in a small spray bottle. Failing that a good set of gloves and some elbow grease after a period of rain when the roots are a bit looser.
About your mystery plant, what about composting the material? Depending on what it is, you could soak the chopped up material in water for a couple days/weeks, use as a "nutrient" tea.. or build a couple hugels on top of them? Or like CJ said, plant some other species around them of asthetically and/or functionally pleasing value to your gramps and make little lawn bouquets! I'm not sure how many folks in here (if any) would recommend any sort of herbicide or pesticide, "organic" or not... If he really wants them gone and is of the "I want a blank lawn" persuasion, maybe this forum could help him/you out..