Yes - in a soil report, the borax is to add boron. In most of the Eastern states and in the Pacific Northwest, soils generally are low in boron. There is a map on the 20 Mule Team Borax site that shows where the low-boron soils are. It's a big area! I am in Georgia, and soil reports from UGA have the recommendation that YOLOS cites, to use one tablespoon of borax for 100 feet of row. Boron is an essential micronutrient, and it is totally possible to use too much. Kelp meal or liquid seaweed (like knittlin suggests) may be safer options than borax, because they are less concentrated. Follow package directions, and the bonus is that lots of different micronutrients will be included, not just boron. Purple leaves on other plants, like tomatoes and corn, often indicate phosphorus deficiency. There can be plenty of phosphorus in the soil, but in cooler weather those two crops can't take up phosphorus as well as they do in warmer soils. Broccoli is a cool-season crop, though, so I would have thought that it could get its nutrients in cooler soil. It's an interesting puzzle! -Amy, who used to work at Cooperative Extension in Cobb County, in horticulture (Earlier this monthI wrote about boron on my garden blog - how lucky is that?)

The cabbage worms seem to stay with the brasica family (cabbage, cauliflower, broccoli, kale. etc). But tomatoes and eggplant can get worms too, although they are a different type. The good news is that BT will get them too. Have you been noticing that the white "butterfly" seems to spend a lot of time around your broccoli. This is the cabbage moth and they are the egg layers that develop into the worms. Other years I waited until I saw the leaf damage before applying BT; this year I started as soon as I saw the white butterfly and I've had minimal worms. When you pick your broccoli, let it soak in a brine solution before cooking and you'll clean out any eggs or worms that survived the BT.

What ever that is it is not black spot. With black spot you get very distinct black spots on the GREEN leaves first. Then the leaf dies and turns yellow and drops. I do not see any black spots on your leaves at all. If the leaves are toward the very bottom and on the inside of the plant it could just be shedding leaves it not longer needs. As the plant grows and leafs out the bottom and inner leaves become shaded and no longer produce food for the plant. The plant then drops them to conserve its resources. Why continue to feed and hydrate a leaf that is longer contributing to the health of the plant?

Several different fungal diseases can cause the leaf spotting shown in the photograph. There are preventative sprays, but none that I know of that provide a cure once the problem is visible. While unsightly, there is no real danger that the infected plants are going to die or lose all their leaves, so most rhododendron growers ignore it. Since it's the lower leaves mostly, they were likely to be ready to fall anyway. Stress from heat or other causes does seem to play a role in encouraging such infections. Picking up and disposing of infected leaves can help in preventing any spread to uninfected plants.