Hello. I have several tomato plants and recently noticed brown spots and holes on the leaves. The basil plants seem to have the same problem. Please advise as to how I can stop this from happening. I have attached a picture of the tomato plant leaves. Thank you.
Thank you for contacting Toronto Master Gardeners.
It certainly looks like something has been having a good nibble at your tomato leaves. There are several different pests that can cause similar types of damage. Leaf hoppers, grasshopper larvae and flea beetles can do this type of damage. It is a good idea to poke around the plants and determine what insect is causing the damage before deciding on a management plan. Try looking closely on the leaves and on the undersides of the leaf to see if you can find the culprit. You may also find them on the stem. If you can get a few into a jar it makes identifying them easier and you can show them to the nursery personnel.
Flea beetles are tiny black beetles that can jump like fleas. For these you will need to visit a nursery and ask for an insecticidal soap that will target them.
Leaf hoppers-they are tiny wedge shaped insects. For these a nursery will also have insecticidal soaps and oils.
The Grasshopper larvae are larger and look more like a really tiny grasshoppers. These require a different treatment again, potentially with sulfur or oils. Your nursery is the best place to find out what is available to use in your area and what will be most effective .
Aphids, spider mites, whiteflies and other soft-bodied pests are all possibilities for what is eating holes in your basil plants. As with the tomato it is important to identify the insect before choosing a solution. You will need to look around the plant and see what you can find.
With any plant in the garden, especially when it is under stress, try to address other issues which could make the problem worse. Make sure they are well watered and that you keep the area clear of any debris that might encourage other diseases to join in. Keep the plants mulched to maintain the moisture in the soil.
Once you have figured out the source of the problem you should be able to get it under control with the correct treatments. I am attaching a two links below, one for tomato and one for basil, that may help with identifying the insect and gives suggestions on further action.