I reduced my bine count per line to 3 (instead of 4-5 last year) and I got the same result. Not necessarily causal, but last year there was so much vegetation up high (and so many f*cking flowers) that a lot of the flowers were smallish and pale. Sort of small acorn size and shape.
I was thinking that too. Maybe also some really hot windy days?If it is localised, I'd say some type of bug is infesting them. I get a little of this every year and remove it as soon as I see it. Could be blight, but it usually starts at the tip and grows up the flower, and does not usually come on until later in the growth cycle...not in burr stage.
Last three days were hot, windy and unusually humid, and this has only occurred on the very small burrs that have developed over the last week.Could be. It looks like they are browning from the stig outwards which is why I'm thinking it may be getting munched on from inside. The outside of the bracts and leaves look healthy.
A bad infestation of spider mites will cause all the flowers on the plant to brown.Last three days were hot, windy and unusually humid, and this has only occurred on the very small burrs that have developed over the last week.
I've been struggling with spider mites, but no evidence of any critters on leaves or in the area. Also starting to wonder if there isn't sufficient air flow around the plants. Some of the cones may be showing signs of tip blight, but as you said it's strange that the burrs are being affected so soon?
I have used them well worth it. we have no tssm on our main plants but our test plants are infected.. You really need to release at the first sign off infection. I would eco oil first then release predatory mites. [emoji4]
I've used both Persimilis and Californicus combined with great success. It's probably overkill for the backyard grower. As Bhundoo said, Eco Oil is an inexpensive option comparatively. They will spread rapidly in the right conditions.