QUESTION: I am having problem with roses, for 4 days i'm observing suddenly flowerbuds are falling off and some rose have got blackness on the edge of petals (don't know what's that called, wings of flower :p ). Why is it happening?Since yesterday two matured flowers has fallen off, and before 5 buds.And strangely drop off happens only overnight , when i wake up n check them (i do so everyday) i see some are broken. What's wrong ?
I'd go out at night and look at the plants with a flashlight to see if you can spot an insect. One of the bugs that does something like this in California is the rose weevil - check this website to see if this is similar to your damage: http://www.sactorose.org/ipm/84rosecurculios.htm
You could try making a garlic repellant by mixing several cloves of garlic into a blender of water, letting it sit for a few hours and then straining the garlic pieces off and using the liquid in a spray bottle. Garlic is a good insect repellant.
If the stem of the rose under the bud is turning black and that's what's making the bud fall you could have stem canker, which is a fungus. Be sure that you're not splashing the plants frequently with water (water deeply less often and try to use soaker hoses that put the water at the base of the plant.) and if you see black or dark raised places on the stems clip those off and start spraying with a Copper based fungicide.
I hope this helps,
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QUESTION: well your expertise is outstanding. Although i think my roses may not have been affected by fungus, it's so because they're never damaged , the ones which had fallen, 5 buds were a little open and some were not and the 2 flowers which have fallen are matured flowers but not that old also, they 'Don't have any damage to them', they're quite beautiful so i kept them on my desk after falling, though the extreme bottom part of stem where the flower broke from remained black for all(but that could be because of drying after breakage). The vendor i bought it from dvice me to keep soil moist always so i water it alternate days and trust me the soil gets rock hard by the time i water it next(here in India temperatures are so).the link you provided helped a lot but none of those conditions are visible in my roses. Now what do you think could be the problem.However, few roses still on plant have become blackish on edges . (Normally the colour is red in small and goes pink when flower matures).
Sorry for the delay in getting back to you about this. My email program has begun blocking All Experts for some reason. I'm trying to figure that out.
The black stem might be a sign of fungal problems. If the soil gets rock hard even tho you are watering every other day, either there isn't enough organic matter such as manure in the soil, or you're not watering it deeply or long enough. A layer of compost or composted manure on the surface of the soil might help keep the soil more evenly moist. when you water the shrub be sure not to get the leaves and flowers wet - that promotes fungal growth. Water the ground only. The black edges could either be fungal or from drying out, or fertilizer burn if you've given it a synthetic fertilizer.
I hope it recovers and that you get great pleasure from the plant for years to come.