Treating Hollyhock Leaf Spots – Learn About Treating Hollyhock Leaf Spots Hollyhocks [1] are charming, old-fashioned plants that are easily recognized by their tall spikes of colorful flowers. Although hollyhocks are relatively problem-free, they are sometimes plagued by leaf spot diseases [2] , especially when it is warm and humid. Rust [3] is the most common.
Recognize leaf spots on mallow
Hollyhocks with leaf spots show small spots that can be brown, gray or brown depending on the pathogen. As the spots enlarge, the dead tissue in the center may fall out, giving the leaves a “shot hole” appearance.
The spots often converge to cover entire leaves when conditions are humid. Under dry conditions the leaves take on a mottled, tattered appearance. You may also notice small black spots that are fungal spores.
Hollyhock Leaf Spot Control
Hollyhock leaf spot diseases, which are usually fungal and less commonly bacterial, are spread primarily by wind, irrigation water and rain. Leaf spot on hollyhocks is usually not fatal to the plant and chemical controls are rarely warranted; Hygiene and proper watering generally keep the disease at bay.
Water hollyhocks early in the day using a soaker hose [4] or drip irrigation system [5] , or simply run a hose at the base of the plant. Avoid overhead sprinklers and keep leaves as dry as possible.
Pick off affected leaves and branches as soon as you notice them. Keep the area under and around plants clean and free of dead and diseased plant parts. A thin layer of fine bark [6] , pine needles [7] or other mulch [8] prevents rainwater from splashing on the leaves. Limit mulch to 8 cm (3 inches) if slugs [9] are a problem.
Thin the plants if the hollyhocks are too crowded. Good air circulation can help prevent hollyhocks with leaf spot and even minimize the disease. Fungicides [10] can be used when new growth appears in the spring when other control methods are not effective. Read the label carefully to make sure the product is suitable for ornamental plants.
Hollyhock Pest Control: Are Mallow Nematodes Good or Bad?
They are jealous of other gardeners’ hollyhocks [ 1] . Their plants are almost 2 m tall and have beautiful flowers in shades of pink, purple and yellow. In comparison, your plants will be stunted with poor flower production. They wilt slightly and look yellowish.
You may not find any signs of bacterial, viral, or fungal infections when you examine your hollyhock. Pest control sprays didn’t help either. Not sure why your hollyhocks are failing. Maybe it’s because the problem lies underground. You may have problems with mallow nematodes.
How do nematodes affect hollyhocks?
Nematodes [2] are tiny parasitic worms that feed on plant roots. They are widespread worldwide and cause problems for commercial growers, greenhouse operators and amateur gardeners. These microscopic pests feast on the roots of many plant species, including cultivated flowers like hollyhocks.
Symptoms of mallow nematodes include poor development and a general decline during the growing season. The plant may appear stunted with yellowed or wilted leaves during the day but recover at night. Digging up and examining the roots of an infected plant can give you the clues you need to suspect that the cause is hollyhock nematodes.
When parasitic mallow nematodes feed, the roots become knotted with visible galls or root swelling. The appearance of root knots and underdeveloped root structures are classic hollyhock nematode symptoms. Nematode-infested roots may also show signs of rot.
Positive confirmation of a nematode infestation can be provided by the Nematode Diagnostic Laboratory. Your local county office can help you collect and ship a sample for testing for a small fee.
Hollyhock Pest Control Methods
Commercial farms rely on chemical nematicides to control nematode populations in their fields. However, nematicides [3] are very toxic and expensive, making this type of hollyhock pest control impractical for the home gardener.
If you have problems with mallow nematodes, try these tips to reduce populations:
If possible, choose nematode-resistant plants [4] . Annual garden vegetables such as peppers and tomatoes are susceptible to nematodes. Growing resistant vegetables can protect your hollyhocks by reducing the population density of nematodes in your garden.
Rotate where hollyhocks are planted. Hollyhocks are short-lived perennials in USDA zones 3 through 8 and are grown as annuals elsewhere.
Alternate hollyhocks with non-host species or those known to reduce nematode numbers. These include broccoli [5] , cauliflower [6] and some varieties of French marigold [7] .
Never move soil from a nematode-infected area to an uninfected area.
Practice cleanliness. Nematodes can ride on tools, gloves, pots and garden equipment like rototillers.
Remove dead plants from the garden. Dispose of infected plants properly.
Keep weeds in flowerbeds and gardens. Nematodes do not distinguish between the roots of unwanted plants and valuable specimens.
Often plant heavily infected areas during the winter months to expose the mallow nematodes to the cold.
Solarize flowerbeds [8] to reduce and eliminate mallow nematode problems.
Finally, healthy plants show fewer signs of nematode damage. Fertilization, watering and proper soil amendment can help your hollyhocks grow into vibrant, colorful flower specimens that are the envy of other gardeners!
Hollyhock Anthracnose Symptoms: Treating Hollyhock With Anthracnose
Beautifully large mallow flowers [1] make a stunning addition to flower beds and gardens; However, they can be put down by a small fungus. Anthracnose [2] , a type of fungal infection, is one of the most destructive hollyhock diseases. Know how to identify, prevent and treat this harmful disease to save your flowers.
Hollyhock anthracnose symptoms
This particular infection is caused by the fungus Colletotrichum malvarum . It is a destructive disease that attacks the stems, petioles and leaves of mallow plants. It’s important to know the signs and symptoms of the disease so you can take immediate action to get the infection under control before you lose all of your plants.
Hollyhock with anthracnose develops black spots on the leaves and stems. The spots can also be brown or red. The disease spreads quickly and the spots may begin to develop pink, slimy spores. You will see black crabs on the stem. Eventually the leaves will wilt, yellow and fall off.
Hollyhock Anthracnose Prevention and Treatment
Anthracnose on hollyhocks is fatal to the plant if you don’t take steps to control the disease quickly. A regular fungicide application [3] can protect and save your plants if applied early enough. Just avoid applying fungicides when temperatures are too high, about 85 degrees F. (29 C) and higher.
Good treatment for anthracnose should also include prevention. The Colletotrichum fungus thrives in warm, moist conditions and survives both in soil and on contaminated plant material. If you have diseased plants that you cannot save, destroy them and remove all dead material [4] from the soil. Disinfect all tools used [5] .
Plant hollyhock flowers with enough space between them to allow airflow to prevent moisture buildup. Avoid watering the plants from above. Watch for signs of infection and treat them early. If you have had problems with this disease before, start treating hollyhocks as soon as they emerge in the spring.
Removing Hollyhock Flowers: Do Hollyhocks Have To Be Deadheaded?
Hollyhocks [1] are the eye-catchers of the flower garden. These towering plants can grow up to 3m tall and produce stunning, large flowers. To get the most out of these beautiful flowers, you should know how to best care for them. Do hollyhocks have to be deadheaded? Yes, if you want them to look good and bloom for as long as possible.
Should you deadhead hollyhocks?
Cutting off hollyhock plants is not necessary, but it is a good idea. It can help blooms last longer throughout the season and make your plants look more beautiful and tidy. Imagine pruning this plant to get it to produce flowers through fall and even the first frost. It’s also a good idea to remove dead and damaged leaves for a better overall appearance and a healthier plant.
Also remember that deadheading [2] prevents or minimizes reseeding. Hollyhock is a biennial in most growing areas, but if you allow the seed pods to develop and fall, they will regrow from year to year. You can prevent this to collect and store the seeds or to control how and to what extent the plants reseed and spread.
How and when to deadhead hollyhocks
Removing spent hollyhock flowers is fairly easy: simply pinch or cut off those that have faded and finished blooming before the seed pod forms. You can do this throughout the growing season. Pinch off spent flowers and dead leaves regularly to encourage more growth and blooms.
Towards the end of the growing season, when most of the flowers have faded, you can shorten the main shoots of your hollyhocks. If you want the plant to come back year after year, you can leave a few seed pods on the stem. These will evolve, fall and contribute to more growth in the coming years.
Removing the hollyhock flowers is not something you need to do to grow this plant, but it benefits the bloom by forcing energy and nutrients into flower production rather than seed production. Keep your head clear to encourage flowering and keep your plants clean and healthy.