Fungal leaf spot or Bacterial leaf spot diseases are likely to ‘eat’ holes in your Zinnia leaves. Aphids are also common pests of Zinnias that eat the leaves. Caterpillars like Leafrollers, Cabbage looper larvae, Army worms and Cutworms can eat holes in your Zinnia leaves.
Zinnia is one of those annuals which can be grown effortlessly. Zinnia produces colorful flowers which one must have in their garden.
I have Zinnia in my backyard and the plant never fails to amuse me. Even such an amazing plant can run into issues.
What is eating holes in my Zinnia leaves?
Holes in Zinnia are not only caused by insects. They are also caused due to a wide variety of diseases. Let’s see the symptoms and remedies of each of ’em.
Fungal leaf spot diseases
Leaf holes can be caused due to a fungal infection. Zinnia is attacked by Alternaria fungus and leaves holes in the leaves.
Initially, you’ll see large reddish-brown or purple lesions on the leaves of Zinnia.
Spots eventually turn gray or tan. Such lesions become irregularly shaped as the fungus eats the leaf. These lesions become bigger and turn into holes.
This disease also causes grayish spots on flowers. This is a sign you can use to differentiate this disease from other similar disorders/diseases.
It is better to prevent this disease as there’s no treatment if the infection is severe.
Tips to prevent:
- Do not water the leaves of the plant. Wet leaves help the fungus thrive.
- Water the plant early in the morning so it has time to dry.
- Spray copper fungicide on the infected leaves. Do this once a week till the spots disappear. This works only if the infection is mild.
- If the infection is severe, you’d have to destroy the plant and dispose of it.
Bacterial Leaf Spot
Not only fungus, but bacteria can also cause leaf spot disease in Zinnia. There are many bacteria that can cause spots and holes on the leaves of Zinnia.
Initially, the spots are tiny, circular. Eventually, they turn into spots with yellow borders. They become bigger and merge with each other.
It is at this point the spots turn black and the tissue dies (Here’s an article on why your Zinnia dies). Dead tissue causes holes in the infected leaves.
There’s no chemical control for this disease. It is best to prevent this disease.
- Do not wet the leaves. Provide good air circulation to the plant.
- The disease primarily enters the plant via wounds. So, do not wound the plant unnecessarily.
- Remove and dispose of the infected plants.
Aphids on Zinnias
Aphids are old enemies of garden plants. They attack many plants. They damage the leaves as they feed on the plant’s sap.
Aphids damage ZInnia by puncturing holes in the leaves. Small populations of Aphids can be controlled by dislodging them with the help of a water hose.
If there is a severe infestation of Aphids, you may want to spray natural solutions like soap-water mixture, Neem oil, or essential oils.
Note: Black bean aphid is the variety that attacks Zinnia. This aphid as its name suggests is black in color.
Do ants eat Zinnias?
Ants do not eat Zinnia leaves. You are probably seeing ants around the plants that are damaged with holes in leaves.
This is not caused by ants although it seems so. Ants carry aphids on their backs and carry them onto your plants.
Ants are attracted by the honeydew secreted by the aphids. Aphids give the ants honeydew for helping them reach the desired host plant.
So, you can control the aphid population by controlling ants. You may want to prevent ants from climbing the plant.
Caterpillars eating Zinnias
Various types of Caterpillars feed on the leaves of Zinnia. Let’s look at them one by one.
Obliquebanded leafrollers love to feed on Zinnia leaves and flowers. These leafrollers are yellowish-brown with black-colored heads.
These caterpillars eventually develop into moths. Leafrollers don’t often infest Zinnias but when they do they feast on both leaves and flowers.
Leafrollers can be a big problem when the infestation is severe. They defoliate the plant and destroy the flower buds before they even bloom.
Armyworms and Cutworms
Armyworms are small and green initially, they turn black, brown, or gray once they mature. Adults of these moths have an orange or yellowish heart-shaped spot.
Armyworms and Cutworms can infest Zinnia. These are serious business and you need to respond as soon as you notice them.
These caterpillars attack flowers and leaves. Armyworms and Cutworms skeletonize Zinnia plants.
Cabbage looper larvae
Cabbage looper larvae are light green in color with white lines running along the two sides of their body. Adult moths have brown forewings that have an eight symbol in the middle.
Younger caterpillars feed on the undersides of lower leaves. As they become bigger they feed on entire leaves and flowers.
Such foliage eating caterpillars cause rapid defoliation, stunt the growth of the plant, and may eventually kill the plant.
The best way to control caterpillars is by controlling weeds around the plants as these hosts the caterpillars. You can hand-pick the caterpillars if the infestation is in an early stage.
These caterpillars can be controlled with Bacillus thuringiensis. Repeated applications help get rid of the infestation.
They can be controlled biologically by introducing Parasitic wasps, Tachinid flies, and Lacewing larvae.
What is eating my Zinnia flowers?
Do you feel that some pest is eating your Zinnia flowers? They might be Earwigs. Earwigs are long-bodied insects that have a pair of pincers in the rear end.
They are coppery red/brown in color. They pass through five stages before turning into adults.
Earwigs feed on the flowers of Zinnia. They usually attack in the summer and fall. They chew holes in the leaves and flowers.
Fans of Zinnia flowers
Earwigs usually eat decomposed plant material. But they feed passionately on the flowers of Zinnia.
Earwigs hide under decomposed plant material in the daytime and prey on the flowers at night. You can trap Zinnia.
How to get rid of Earwigs on Zinnia?
You can trap Earwigs by placing a bowl of vegetable oil near the infected plant. One can also trap them using rolled newspaper.
Now destroy the trapped Earwigs by dropping them in soapy water or rubbing alcohol.
You can control the Earwig population by spraying Imidacloprid over the infected area. You may spray 4 to 8 ounces per 1000 sq ft, depending on the severity of the infestation.
Do slugs eat Zinnias?
Yes, slugs do eat Zinnias. Slugs love to eat the foliage of Zinnia. They are pesky pests that are most active at night time.
Slugs leave shiny trails as they move ahead. You can find their presence with these trails. Slugs attack Zinnia in summer and spring.
They feed on Zinnia leaves at night. Slugs chew on the leaves, leaving holes in them.
You can hand-pick these pesky pests at night and throw them into a bucket of soapy water. This would get rid of them if they are in low populations.
If there’s a large population of slugs, they can kill the plant.
To control slugs
- They hide under debris where it’s moist. Make sure there are no such spots around the plant.
- You can use wet newspapers or shallow bowls of beer to trap slugs. Then, you can throw the trapped slugs into a bucket of soapy water.