Answer: Based on your description, I am not certain what is happening to your Thunbergia vine. This plant is usually trouble free so there is no common culprit to suggest. The eaten flowers might be the result of caterpillars such as budworm. Look for these in the late afternoon or early evening, they often tunnel into the bloom before the bud opens as well as eat the opened flowers. They are difficult to treat but handpicking and Bt (Bacillis thuringiensis) can help with caterpillars. The blackened foliage might be due to a fungal infection such as botrytis which develops under certain weather conditions. Try to keep the leaves dry, improve the air circulation, and remove the affected foliage and dispose of it in the trash to limit sources of reinfection. You might also want to consult with your county extension to obtain a more definite diagnosis and based on knowing that, determine how to proceed. In the meantime, I hope this helps.
Q&A Library Searching Tips