I was looking for some assistance. I have a Japanese Maple that was thriving a few weeks ago and now some of the leaves on a few branches look burnt and shriveled up. I am not sure if this is sun damage, the tree is dry or if something is attacking it. Please help!
Also, every year around this time, or just before Fall, I notice my potted petunias start to get attacked by some bugs and die out. Lately I am noticing many earwigs in and around the pots, also these tiny black eggs, and green bugs all around the flowers. A few of the flowers also have holes in them. I have been picking the dead flowers out but cannot keep up. The flowers just look like they are starting to die out more and more, and I feel like its the bugs toward the end of the season but I am not sure.
Thank you for contacting the Toronto Master Gardeners. Regarding your Japanese maple, since it was thriving until a few weeks ago, I think the shriveled leaves you are seeing are the result of leaf scorch, caused by the weather we have been experiencing. Japanese maples are prone to leaf scorch. Prolonged high temperatures, hot and drying winds, and low rainfall are the most common reasons for leaf scorch. With these weather conditions, large amounts of water evaporate from the leaf surfaces, and the plant roots are unable to provide enough water quickly enough to replace what has been lost by this transpiration. Leaf tissue dies as a result. Typically, leaf scorch appears in July and August, on the side or sides of the plant most exposed to sunlight and prevailing winds. Plants may lose some leaves as a result of leaf scorch, and it can weaken the plant, making it more susceptible to insect infestation and disease (Japanese maples usually have very few of either one), but leaf scorch alone won’t kill a plant. A few things you can do for your Japanese maple are :
- Give it an extra deep watering every week or 10 days, while the weather is hot and dry. Japanese maples prefer moist (not wet) well-drained soil.
- Add about 3-4 inches of organic mulch to the surface of the soil under your tree (a few inches away from the trunk), if you haven’t already, to conserve soil moisture.
- Help your tree to stay healthy with annual fertilization in the early spring, based on the results of a soil test.
Regarding your petunias, I would need a clear close up picture to be certain about what insects are infesting your plants. Earwigs generally do not cause major damage in the garden. In fact, they can be beneficial because they control other insects including aphids, which could be on your petunias. More about earwigs here. The tiny black eggs that you are seeing could be not eggs but droppings from thrips, or they could be spider mites, both of which are common insects on petunias. The green bugs could be aphids or cyclamen mites.
Please note that the information about pesticides (chemical controls) in the links above applies in the US and not in Canada. The use of pesticides in Ontario for cosmetic purposes in home lawns and gardens is strictly controlled by law. Here is an Allowable list of active ingredients that can be used in Ontario.
Petunias usually have few serious pests or diseases. Healthy plants are better equipped to ward off insect infestation and disease than plants that are under stress from unfavourable environmental conditions or improper care. In order to thrive, petunias require at least 6 hours of full sun daily. The soil should be well-drained, and they should be watered when the soil feels dry a couple of inches below the surface. They should be watered deeply and less frequently vs frequent shallow watering. They should be fertilized either with a slow release fertilizer added to the soil when they are planted (in containers) or every 2-3 weeks beginning in July with a liquid fertilizer for flowering plants (follow the instructions on the label).
We would be happy to help with insect identification if you would like to submit another question that includes a close up picture and detailed description of what insects you are seeing (use a magnifying glass) and the damage they are causing.
Best of luck with your Japanese maple and your petunias.