Broccoli leaves turning yellow/brown on edges

My broccoli plants looked so healthy up until now. The leaves are turning yellow and then brown on the edges. I was wondering if this could be a deficiency in something and how to correct it. Anyone have this problem?

Might it be sunscald? I don't know about WI, but we have been considerably hotter than usual, and I've had to shield some plants.

Could you post a picture of your broccoli? That would help us to help you make a Dx.

Linda

It has been a cooler summer here so far so I doubt it is sunscald. I will try to post a picture of it tomorrow. Thanks.

Here's the picture of one of the broccoli leaves. They don't all have it, but it seems to be spreading each day.

ShelleyF,
I found this online. If you've not had an abundance of rain, or are not over watering, then I venture to say you have a nitrogen deficiency. My suggestion is to sprinkle either some blood meal or ammonium sulfate, and work it into the top 3" of your soil, around the base of the plants. Water it in.

In brief:
• Both Ammonium Sulfate and Ammonium Nitrate are salts of ammonia.
• Both find use as soil fertilizers, but while Sulfate ions are suitable for alkaline soils, nitrate ions are more suitable for acidic soils.

Read more: http://www.differencebetween.com/difference-between-ammonium-nitrate-and-vs-ammonium-sulphate/#ixzz37Ylq04hr

Three common conditions can cause broccoli to yellow in the garden.

Broccoli (Brassica oleracea) is a floral vegetable belonging to the cabbage family. It is a cool-weather crop grown for its edible head. It needs full sun and moist, sandy, nitrogen-rich, slightly acidic soil. Sometimes broccoli plants turn yellow instead of a healthy green. Three common conditions cause broccoli to yellow in the garden:

►Maturity Yellowing
The head of broccoli is actually made up of many tiny flower buds or florets. If left unharvested, broccoli heads mature into a multitude of tiny, bright-yellow flowers that produce seeds for another generation. As the heads mature and the flower buds start to swell, the heads become more and more yellow until the flowers burst forth. Yellowed broccoli heads turn bitter and lose their nutritional value.

►Nitrogen Deficiency
Broccoli is a very heavy feeder that requires high levels of soil nitrogen. Broccoli leaves turn yellow if the plant isn't getting enough nitrogen. With nitrogen deficiency, the bottom leaves turn first and the problem continues upward toward the head. In extreme cases, the entire plant turns yellow, wilts and dies.

►Fungal Disease
Yellowing of broccoli plants may also be caused by the fungus Fusarium oxysporum. This ground-dwelling fungus enters plants through new roots and older roots wounded during transplanting. The fungus works its way up the stem, causing leaves to turn yellow and fall off. The stems become stunted on one side, causing them to curve. The fungus eventually kills the plant.

Dealing With Yellowing
Head yellowing in the garden is simply the result of waiting too long before harvesting. Take the main head or side shoot when it ceases to expand, while the flower buds are plump but still green. Treat nitrogen-deficiency yellowing with a fertilizer high in nitrogen but low in phosphorous. If you are growing organic broccoli, fertilize the plants with blood meal.

Prevent nitrogen deficiency by fertilizing at planting, when the main head emerges and after the first heads are harvested so side shoots grow. There is no cure for Fusarium yellowing. Once this fungus establishes itself in a garden, the only successful control is to plant broccoli varieties resistant to this disease.

Hope this helps.

Thank you so much, Gymgirl. Wow! Lots of good information. I'll try the blood meal and see if it works.