Why do plant leaves stick?

27 August 2022

What does it mean when something like glue appears on the leaves of a plant and to what extent should we be concerned?

Glue on the leaves is a characteristic symptom that indicates the presence of an insect or a disease on the plant. Usually the glue on the leaves has a transparent color, but there is also white glue, while in some cases they can acquire a black shade.

The sticky substances prevent the plant from growing normally and gradually weaken it, causing problems in growth, flowering and fruit production.

Leaf spotting is a problem that affects all plants, from our garden flowers and houseplants, to our herbs, horticulture and garden trees.

As with other leaf symptoms such as browning of leaves, yellowing of leaves and curling of leaves, it is important to identify the problem promptly so that appropriate measures can be taken.

So let’s look at the main causes that cause glue on the leaves, which plants and crops are affected, and how we can deal with them in an ecological way to keep our plants beautiful, healthy and full of life.

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Why do leaves have glue and how do we deal with it?

The appearance of the glue on the leaves of plants is due to attacks by insects and diseases, as we describe in detail below along with the appropriate ways of ecological treatment.

1. The leaves stick due to an attack by aphids, the well-known meligra

Meligra insects look like small lice that suck plant juices and leave a sticky substance on the leaves.

We will meet them in young shoots and leaves of vegetables such as in the tomato crop, the cucumber crop, the pepper crop, the pumpkin crop, the corn crop and the artichoke crop.

Leaf spotting due to meligra is seen in several ornamental plants, such as roses, hibiscus, petunias and chrysanthemums, as well as aromatic plants such as basil, mint and spearmint.

Meligra also occurs on fruit trees such as lemon, orange, apricot and pomegranate.

To deal with meligra we spray the plants with biological insecticides such as summer pulp, natural pyrethrin and potassium salts. Alternatively, in cases of mild infestation, we can spray with an improvised preparation made by dissolving 1 tablespoon of grated green soap and a teaspoon of alcohol in 1 liter of water.

Aphids, 5 ways to deal with meligra

2. Leaves stick due to mealybug infestation

The mealybug is a small insect that looks like a white mosquito or whitefly that usually hides on the lower surface of the leaves and we can observe them flying by dozens if we shake the plants.

Like aphids, mealybugs attack most plants in the summer vegetable garden, where they secrete a sticky honey-like substance, leaving a transparent glue on the leaves.

It also occurs in fall vegetables such as the cabbage crop, the lettuce crop, the broccoli crop, the cauliflower crop and the spinach crop.

Treatment of powdery mildew in the garden

Powdery mildew also occurs in citrus fruits, lemons, oranges, tangerines and grapefruits, creating a white glue that makes the leaves look like snow.

Treatment of powdery mildew in lemon, orange and tangerine trees

To deal with powdery mildew in citrus, we spray the leaves with organic insecticides such as potassium salts and summer pulp.

In the vegetable garden, we use yellow traps with glue that attract mealybugs and in cases of increased population we spray with potassium salts to deal with mealybugs.

Insect traps with glue for protection in the garden

3. Leaves stick due to cotton blight infestation

The cotton bug is a granular insect surrounded by a distinctive white filamentous cotton-like sheath.

It usually appears on the lower surface of the leaves and at the junctions of the leaves with the stems, leaving a sticky substance on the plants.

Cottonseed attacks many ornamental plants such as gardenia, camellia, hydrangea, bougainvillea, angelica and dipladenia.

We will also find it on the vine, in citrus trees, and in subtropical plants such as banana and mango.

To treat cotton blight, spray the plant leaves with summer pulp combined with natural pyrethrum and repeat after 10 days.

How to deal with cotton in plants

4. Leaves become sticky due to disease attack

In fruit trees such as in apple cultivation, pear cultivation, medlar cultivation, peach cultivation, apricot cultivation and plum cultivation, we can observe characteristic drying of the leaves and rotting of the fruits, often accompanied by secretion glue due to infestation by the fungal disease monilia.

To control monilia disease, we spray fruit trees with copper formulations in late winter before new growth develops and in spring when the fruit trees begin to flower.

What happens when there is resin-like glue in the trunk of plants?

If we notice resin-like glue on the trunk of fruit trees such as lemon, orange, tangerine, apricot, peach, plum and cherry, it is probably due to the disease Phytophthora sp. which can still dry out the trees.

To deal with phytophthora, we smear the trunk and water the root with a copper sulfate solution.

Combing, treatment of phytophthora in fruit trees

And a secret about the glue in plant leaves

The glue left on the leaves by the mealybug, mealybug and cotton insects is a pole of attraction for the tobacco fungus, which feeds on the honeydew of the insects, causing browning of the leaves and a reduction in the photosynthetic capacity of the plants.

Smoke tan occurs along with honeydew secretions from insects Share this article with your friends: