What Are the Small Black Dots on the Leaves of My Petunias?


Petunias (Petunia spp. ), which are produced as annuals most of the time despite the fact that they may live as perennials in the plant hardiness zones 10 to 11 of the United States Department of Agriculture, are treasured for their many potential growth patterns and their gorgeous blooms. There is a wide variety of flower colours, colour patterns, and styles to choose from when purchasing one. If you are appreciating your favourite petunia and discover some little black spots on the plant’s leaves, you may get concerned about the plant’s health. In most cases, doing a thorough examination of the petunia plant and noting the occurrence of any other symptoms will result in the discovery of more hints about the likely offender and will direct the selection of an appropriate remedy.

A Pest of Many Plants

The tobacco budworm, also known as the geranium budworm or the budworm caterpillar, is the larva of a moth that as an adult has wings that range in colour from light green to brown and that have a wingspan of 1 1/2 inches. Eggs may be laid on either buds or leaves by the adult female moth. After hatching, the larvae, which may range in colour but often have distinct banding, eat inside the growing flower buds of the plant until they are ready to emerge and feed in the open as the plant continues to mature. Flowers either do not bloom at all or blossom but have an irregular look. In the regions where these caterpillars eat, there are spots of excrement that look like tiny black seeds that may be seen.

Nip it in the Budworm

Regular monitoring performed at the beginning of the growth season may help prevent the damage caused by budworms, particularly if the budworms are caught in the early part of the growing season while they are in their first generation, which is normally smaller. The caterpillars may be hand-picked and then placed in a pail of soapy water, which is one of the most efficient techniques for controlling budworms. Dusk is the time of day when the budworm is most active, thus it is recommended by the Colorado State University Extension that you search for this pest at that time. In most cases, budworms may be controlled by spraying petunias thoroughly with a solution that contains Bacillus thuringiensis, sometimes known as Bt, using a garden sprayer. This should be done as soon as the pests are discovered. (For each gallon of water, use about 12 tablespoons of Bt.) In any other case, ensure that the petunias get proper cultural care and that the space surrounding them is clear of weeds that may serve as hiding places.

Distortion, Stippling or Color Break

There is a risk of western flower thrips infesting petunias and other ornamental and garden plants. Western flower thrips are very little insects with a body that ranges in colour from yellow to orange and wings that are fringed. The feeding of thrips may be identified on flower petals and foliage by the appearance of stippling, scarring, and deformed or stunted development. There are various organisms that naturally prey on thrips. Predators are able to exert effective control over this bug if dusty circumstances are kept to a minimum and broad-spectrum insecticides with a permanent effect are avoided. Petunias and other plants that are afflicted with thrips and other harmful insects and mites may have the thrips and other pests removed from the plants by periodically spraying them with a strong stream of water. Petunias that have been given great care, which includes an adequate amount of watering and a reduction in the amount of nitrogen fertiliser they get, are more likely to be able to survive and swiftly recover from thrips feeding.

It Could be Nothing

If the petunia is in good condition and there are no symptoms of pests or signs of feeding, then the presence of tiny, black spots may not be cause for concern. In the event that you let wasted blooms to go to seed, the little black specks you observe may quite well be petunia seeds. Find a spent bloom on the plant that has already started to grow into a little capsule so that you may put this idea to the test. Then, using your fingers, break or open the capsule, and examine the seeds inside to determine whether they are similar in appearance to the black spots on the petunia.