After the last heavy rain period one week ago, I noticed a kind of scab on a few rose hips. If I am right with this assumption, this is a fungus, which is much better known from apples and plums.
The best condition for scab infestation seems to be several hours of wetness, high humidity (80 %) and temperatures above 5°C. The longer the moisture lasts and the higher the temperature, the faster, usually within 10 hours, the infection occurs.
Do you have also ocassionally noticed this phenomenon on hips? If I remember correctly, I have seen it to a much lesser extent even already in other years, but I didn’t attach much importance to it, because I stratified the achenes together, within one and the same crossing, regardless of the infection of the rosehip. It is therefore not possible for me to judge in retrospect whether already the slight scab attack had a detrimental effect on the achenes or their germination behavior. In any case, I didn’t notice anything in particular.
This year the infestation on a single rose hip is partially stronger, why I would be grateful to know, whether there are any further findings or observations, especially if the possible genetic predisposition to do so from experience relies more within the modern varieties? The two roses in question are both ‘Modern Roses’. Thanks for time and comments!
It doesn’t appear to be fungal to me from your photo. It’s more like the sudden intake of water from the rain caused the cuticle of the hip to crack, like painting a balloon then inflating it.
I agree, this looks more like russeting. It seems to be pretty uncommon, but I have a seedling that can produce hips with very heavy, even russeting all over the surface–it doesn’t seem to do any harm.
@MidAtlas, many thanks for comment and sharing your observation! The photo in the sunlight this morning gives additionally a clearer picture of color and structure without Macro enlargement. When you touch the areas, it really does feel like a rusty apple.
I know this occurrence too, there are a few of them almost every year. What I have noticed is that these rose hips are empty. So far, I have interpreted it as meaning that the cross failed and that some environmental influences, even a lack of nutrients or water, have caused the plant to get rid of unnecessary ballast due to resource conservation by interrupting the supply completely. Maybe there are some other theories.
