What could cause a burn like this. DDVP in an autofog was used prior to burn. Bracts were in colour during chem application.

Sometimes chilling can cause similar display. Check for drafts. Did you have a cool night during your fog?

This also looks like a situation where maybe bract edge burn lead to botrytis setting in. Are you making weekly foliar sprays of calcium? Have you applied anything for botrytis?

Spotting and burn from foggers I have seen in the past usually looks like many tiny spots on the bracts and foliage, or larger areas where water droplets on the foliage have concentrated the chemical that was used in the fogging. Your burn on the bract edges does not look like a burn from the fogging process to me.....Michael Pawelek

Mark, this looks like it is on Prestige – correct? Are other varieties affected? Is this wide spread or just on a few plants in an isolated area? The blue color is probably Botrytis. So the question seems to be what was the initial problem that allowed the Botrytis to get started. If this is widespread, then it may be Bract Edge Burn related to low calcium tissue levels that will allow Botrytis to get established in what looks like healthy tissue. If this is the case look at the Ecke information on Bract Edge Burn for control measures. Jim

Yes, they are prestige. The bract problem is ONLY happening to prestige.
Is prestige more susceptible to bract edge burn (calcium deficiency, etc)?
Could this be from DDVP or Nova?
There was one morning temps were down to 9C for 1 hour.

We have had the leaves and bracts analyzed. Here are the results.

Leaf:
N 5.66%
P 0.5%
K 1.97%
Mg 0.78%
Ca 1.45 %
Zn 33.03 ppm
Mn 106.55 ppm
Cu 8.20 ppm
Fe 171.80 ppm
B 47.44

Bract:
N 3.35%
P 0.53%
K 4.32%
Mg 0.24%
Ca 0.20%
Zn 28.80 ppm
Mn 10.21 ppm
Cu 5.01 ppm
Fe 76.58 ppm
B 25.60 ppm