We were at 8 weeks on our black bean plants beautifully making their way up the trellis, when we decided to treat the leaves with Neem oil spray. A number of holes had appeared in the leaves which we presumed to be the result of aphids. We applied the Neem spray at 6pm. Instructions on the bottle asked the user to spray so that leave was saturated, and that to be effective, entire plants needed to be sprayed. The following days, the lower leaves turned yellow and began falling off. Tested soil: pH of 7.8 (slightly alkaline), and moisture meter (which shows indications of dry, moist, and wet) has the needle pointing halfway between moist and wet. I'm thinking that the runoff of the neem oil in the soil causes inability of root system to take up iron, or nitrogen, or both. Going to add 2 teaspoons of vinegar to gallon of water for next watering, and going to spread coffee grounds to add some nitrogen to soil. Any other ideas would be greatly appreciated as it is disappointing to see the plants suffer this late in the season.

For some reason this old posting showed up on my ipod this morning. I was surprised that this is almost exactly what my older trees have. Too bad this is an old thread because I would have liked to ask the OP if the spots washed off.

According to the "book" and what I've read thornless don't yield as much. Whether it's enough to matter to the average homeowner I don't know. Also IME Persian Limes (especially) & Key Limes are very underrated for their cold hardiness. TRUE Lemons are over rated. I have about 20 citrus trees in the ground and my Tahitian lime is one of the hardiest & most cold hardy here in zone 9B. The only citrus trees I have ever lost to low temps were a full sized Harvey Lemon and a mid sized Varney Navel tree back in our record 2010 freeze here when he got down to about 20. Nothing else even got burned. I have seen a lot of nurseries saying Tahitian limes are cold sensitive and I have not found that to be the case. Lemons I have.

Janette: You have been having hot temp, leaves are wavy, and water has not drained out of the pot so you may be under watering, It is hard to tell. This is how to tell if the tree needs watering: take a 1/4 inch dowel sharped to a point or a shish kabob stick and stick into the soil all the way to the bottom. Wait about 5 seconds and pull it out. If there are soil particles sticking to it or if it feels cool and damp then it does not need water. It is important to let water drain from the bottom, to prevent buildup of salts. Laura: Some of my trees do that, too but the leaves are not yellow ,they are not dropping leaves and they seem to be OK. I don't know why they do that. I admit it does worry me sometimes. It's like taking care of kids, isn't it? Like when they get a fever and you worry.