Browse below for some information

on common plant problems ::

(click on photos for enlarged versions, new window/tab will open,

more photos and problems often added)

Iron Deficiency

Iron Deficiency on Petunia

Cause: Iron deficiency (lime-induced chlorosis) is a common problem in many annual and perennial plants, especially Petunia, Bacopa, Scaevola, and numerous others. It can occur for many reasons, but typically it happens because the pH of the soil becomes too high for the plant to absorb iron. Iron deficiency also frequently occurs in containers, where necessary constant summer watering leaches out nutrients in the soil. If not taken care of, iron deficient plants gradually lose foliage and die.

Symptoms: Lighter green foliage, especially towards the ends of the stems or on newer growth. Veins stay darker green. In extreme cases, foliage turns completely white and then shrivels to a tan-brown color. Flowers often are smaller in size.

Cure: For gradual improvement, fertilize more. For example, instead of feeding once a week, feed every day for a few weeks. Or, instead of feeding 1 tablespoon per gallon, mix 2-3 tablespoons per gallon (Peters, Miracle-Gro, etc.). You should see improvement within a few weeks, with foliage greening up and new growth appearing. For faster results, you may follow directions on any chelated iron product and add that to your fertilizer water (this type of product makes iron readily available to the plant). This will green up the foliage quicker, but be careful to follow directions.

Bottom Line: Keep your plants healthy, and learn to identify nutrient-deficient plants before it becomes a problem. Feed regularly, especially if in a container or basket.

Mildew or Powdery Mildew

Left: Mildew on Tall/Garden Phlox foliage

Middle: Mildew on Zinnia foliage

Right: Bottom foliage on Tall/Garden Phlox resulting from mildew

Cause: Mildew is usually a problem caused by either growing conditions (weather, warm days and cool nights, humidity, etc.) or simply an unavoidable natural condition of certain plants. Mildew (fungi) appear on leaves which eventually hinder sufficient uptake of light and prevent normal plant processes. Some plants that are susceptible to mildew are Tall/Garden Phlox, Monarda (Bee Balm), Pulmonaria, and many annuals.

Symptoms: White, black, or brown splotches or overcasts on leaves. In extreme cases, foliage turns a crispy tan or brown. Entire plant appearance deteriorates.

Cure: Ultimately, try and choose plants that are mildew resistant. Chemical treatment periodically throughout the season with a fungicide specifically for mildew will minimize fungi growth, but it will not guarantee a completely mildew-free plant. Cut back plants to eliminate undesirable foliage and keep air movement at a maximum. Keep plants that are susceptible to mildew moist but well-drained. 

Bottom Line: Accept that certain plants will get mildew to a certain degree, no matter what you do. Fortunately, most plants that are susceptible to mildew usually are done blooming by the time it is a serious problem.

Aphids

Left: Aphids, Aphid larvae, foliage damage on Hemerocallis

Right: Aphids, distorted foliage on Pelargonium

Cause: Aphids are one of the most common garden pests known. They colonize and feed or "suck" plant juices from leaves or stems. Aphids reproduce rapidly and they are not particular in what they choose to attack, as they have been found on just about every type of plant.

Symptoms: Clusters of Aphids are found on the plant, usually but not always near the tips of the stems or buds, or deep within the leaves towards the base of the stems. They can be black, brown, or green, and are typically the size of a ballpoint pen tip. Foliage that is distorted, curled, scarred with tiny yellow spots where it has been sucked, or blackened by the residue left behind by the Aphids. Tiny white shells left behind by hatching eggs.

Cure: Chemical treatment can be done any time they are seen, and any pesticide specifically made for Aphids can be applied regularly to minimize and eliminate populations. Use as directed! Repeated applications are necessary to eliminate existing insects and possible eggs/larvae that might hatch a few days later. Natural solutions often include ladybird beetles (predators of Aphids) or insecticidal soap, both of which are effective but sometimes are not as convenient or produce immediate results as compared to chemical treatment.

Bottom Line: Early identification and treatment is key. If a colony of Aphids is left untreated, serious damage to the plant will occur.

Japanese Beetles

Japanese Beetle damage on Malva

Cause: Japanese Beetles have become quite a nuisance in recent years. They feed primarily in July and August, and can defoliate plants with incredible speed. Many plants are resistant to Japanese Beetle, but the vast majority of plants are not immune to this serious pest. 

Symptoms: Single beetles or clusters of them are found on the plant. Irregular holes are eaten away from the leaves, leaving only the veins.

Cure: Chemical treatment can be done during active feeding months, and any pesticide specifically made for Japanese Beetle can be applied regularly to minimize beetle populations. Traps can also be used, and can keep the beetles from producing next year's beetles. Traps should be placed away from your gardens so as not to attract more beetles to your plantings. Biological controls such as parasites, fungi, and nematodes have also proven to have some limited success.

Bottom Line: Japanese Beetle will most likely be a permanent pest for our gardens and plants. However, they can be kept in check with simple traps and minimal application of chemicals. Use as directed!

Slugs

Slug damage with tell-tale shiny trail

Cause: Slugs can be a nuisance in any garden, and can be found in virtually any yard or garden where cool and moist areas are prevalent. They are night feeders, so it is very likely that you may not notice them right away. Slugs will feed on many different plants, but especially Hosta, Delphinium, Marigolds, and other plants with leafy and fleshy foliage.

Symptoms: Irregular holes in leaves. Clear, shiny silvery trail left behind by the Slug's mucus body on top side of leaf.

Cure: Many methods are available with reportedly varying results. Beer in an upside-down jar lid, store-bought traps, salt, slug fences, copper rings to surround the plant at ground level, and store-bought slug bait or pellets which deter or kill Slugs.

Bottom Line: Always expect a little damage to your plants if you have consistently moist and rich soil, especially in shaded areas. Usually none of the methods above are really necessary unless there is a serious infestation of Slugs. If there is, simply use what works best for you.

Spider Mites

Left: Spider Mite damage on Garden Mums, discolored leaves

Right: Spider Mites on New Guinea Impatiens, webbing

Cause: Spider Mites, yet another garden pest, can be a difficult problem to cure. Spider Mites suck on leaf tissue, multiply rapidly, and are difficult to identify because of their small size. Many times when you discover Spider Mites, it can be too late for a quick cure to the problem, and ultimately, the plant is beyond a cure.

Symptoms: Small, circular white spots on leaves, and in extreme cases, leaves turning a light tan. Fine, small web-like structures on top of or on the underside of the leaves. Tiny insects residing within the webs and crawling on leaves. Webbing and damaged leaves are usually found on newer growth or at the ends of the stems.

Cure: Use a pesticide as directed that is specifically made for the control of Mites or Spider Mites. Apply regularly and frequently. Pruning off damaged foliage will help to get rid of some of the insect population.

Bottom Line: Learn to see the symptoms right away so action can be taken quickly to remedy the problem. Keep plants healthy so that even if there is a minor infestation, it does not become severe.

Winterkill

Cause: Some perennial plants, even those that are supposed to be winter-hardy for your area, may die and/or not come out of dormancy in the spring. This can be caused by 1) temperatures dropping below the normal winter lows of your particular area, which may be too cold for your usually "hardy" plants, 2) late planting in the fall which does not allow enough time for plant to get established, 3) sudden cold temperatures in the fall before the plant has enough time to store up sugars ("anti-freeze" protection) for the winter months, and 4) plants being too stressed out and unhealthy prior to the winter months thereby not having sufficient health to survive the winter.

Symptoms: Plant does not show any sign of life during the spring months when they should be coming out of dormancy. Plant may look brown or black, it may be mushy or rotted, and no healthy roots can be found below the soil surface.

Cure: Always choose plants that are correctly and accurately labeled as being hardy for your zone. Try to have all of your perennial planting done by late-October or early-November. Keep your plants as healthy as possible by adequate watering and feeding, especially during the late summer and fall when you may think everything is "done for the year."

Bottom Line: Climate and temperatures are out of our control, but doing your best with what you can control will certainly help your chances at receiving reliable performance each and every year from your perennials.

Notice ::

Information displayed above is for informational purposes only. W.W. cannot assume responsibility for further plant problems resulting from actions taken as advised above.

Top of Page