8 Different Tulip Diseases: Identification, Prevention, and Treatment
Does your tulip have a disease that you've struggled to identify? There are a number of common diseases that can plague tulps each season. In this article, certified master gardener Liz Jaros walks through the most common tulip disease and how to identify, prevent or treat them.
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A symbol of hope and rebirth, spring tulips are typically a delight for tired winter eyes. You’ve been waiting patiently for them to pop through the gray landscape and bring color back to the garden. You’ve selected your bulbs carefully, followed all planting directions, and put them to bed lovingly in fall.
So why aren’t your tulips growing as you’d intended? Do they look ragged or wilted or stunted? If something seems off with your tulips’ color, stature, or performance, they may be suffering from a disease.
While tulips do have a few common pests, they are not particularly vulnerable to many viral or bacterial conditions, they can fall victim to a few diseases you’ll want to watch for. Here’s a look at some of the most common tulip diseases and some suggestions for identifying, preventing, and treating them.
Tulip Fire
Also known as botrytis, tulip fire is perhaps the most well known disease to afflict the genus. A fungal condition that can attack all parts of the plant, this disease is a threat to all commercially grown tulip species and cultivars.
It can be present in the bulb at time of planting or transmitted during the growing season. It’s popular with many plants grown from tubers. Popular flowers like dahilas can also suffer from the condition.
The first signs of this disease are small, twisted shoots called ‘fireheads.’ These shoots appear mottled or blighted and will eventually collapse. Soon after, gray-brown wet spots will appear on leaves and/or blooms to indicate the presence of mold spores. If not handled swiftly, these spores will spread rapidly through your flower bed and possibly to your lilies.
How to Identify
Look for twisted, stunted shoots and gray-brown, water soaked spots when weather is wet. Look for brittle or split leaves with tiny spots in periods of drought. If tulips have blooms, petals may have white or brown soft spots.
How to Prevent
Always purchase bulbs from a reputable grower. Make sure they are firm and unspotted before planting, and space properly for good airflow. Remove fallen petals and debris often from beds. Take care to water without drenching leaves. Rotate your beds every year to break the fungal cycle.
How to Treat
Unfortunately, there is no cure. Infected plants should be disposed of immediately (not composted) and beds should be monitored carefully for signs of spread.
Basal Rot
In times of unusually high humidity and temperature, your tulips may suffer from basal rot. Small white to pink spots or large brown spots on an unplanted bulb indicate the presence of this fungus, and it should not be planted.
Above ground signs of this condition include foliage that dies prematurely and/or deformed or non-growing stems and flowers. When dug up, roots will appear mushy and might have a foul odor.
How to Identify
White, pink, or brown spots on bulbs are early signs of basal rot. Dying foliage, absent or deformed flowers, and stem collapse are also symptoms. Roots might be slimy and foul smelling.
How to Prevent
Again, responsible bulb sourcing is key to prevention. Consider purchasing bulbs that have been treated with a preventative fungicide. Take care not to injure bulbs (or plant injured bulbs) as this encourages fungal entry. Watch for signs of spread.
How to Treat
Excavate infected bulbs, plants, and their surrounding soil immediately.
Root Rot
A disease caused by the fungus pythium, root rot typically attacks juvenile bulbs and seedlings. Also known as water mold, pythium is present in all soils and activated in overly wet conditions.
Attacking roots first, pythium will cause them to turn brown or black. If there is growth above ground, plants may stop growing and collapse. Bulbs will eventually shrivel and shrink to a small black core.
How to Identify
If tulips have not emerged, check roots for signs of rot. They will appear brown or black beneath the basal plate. Color may spread upward and affect shoots. Shoots may not emerge or will appear stunted and weak. Bulbs may be shrunken or black.
How to Prevent
Use chemical or steam-treated potting mix to discourage root rot. Do not plant bulbs that feel light in your hand or have a mealy consistency. Make sure soil drains evenly and irrigation is not excessive. Use pine bark mulch to insulate, as it is known to offset pythium.
How to Treat
Infected plants should be discarded along with their surrounding soil.
Crown Rot
If you notice something fungal happening at the soil level, or low on your tulips’ stems, it may be crown rot. Look for a reddish tint on stems and possibly leaves to indicate the presence of sclerotiium delphinii. Thready, white mushroom-like strands will eventually cover the lower stem and bulb.
Bulbs can be infected if they are stored in a warm, humid place during dormancy. And the condition spreads quickly to nearby plants. Sclerotiium can live in the soil for many years, so take care to remove as much of the surrounding dirt as possible, if crown rot is suspected.
How to Identify
Leaves or stems with a reddish tint are early signs of crown rot. Thread-like, white strings develop later around the crown, stem, and bulb. Tulips will be easy to break off at ground level.
How to Prevent
Always store tulip bulbs in a cool, dry place until you are ready to plant. This applies to bulbs that have been purchased as well as those that have been excavated. Use new bags of potting mix that have been sterilized. Handle bulbs carefully when planting.
How to Treat
Dig up infected plants and dispose of them. This fungus does not spread particularly fast or last overly long in the soil, so nearby plants should be okay unless symptoms are observed.
Bulb Nematode
This disease is the result of microscopic creatures depositing bacteria that attack a tulip’s stem and/or bulb. Plants afflicted with nematode disease will often be clustered together. They will have yellow, wilting leaves and may die back prematurely.
Bulbs may have gray to brown spots that are spongy and will be lighter in weight than healthy bulbs. Nematodes can spread in water, soil, seed, and plant debris.
How to Identify
Leaves may be yellow and wilted or collapsed. Affected plants will be clustered together. Bulbs will be spongy and light with a mealy texture.
How to Prevent
Purchase bulbs that have been pre-treated for nematodes. Make sure bulbs are firm, properly colored, and of average weight. Disinfect tools regularly to prevent cross-genus spread. Rotate your flower patches annually.
How to Treat
Remove infected bulbs immediately and dispose of them. Sterilize or excavate the soil in which affected tulips were growing.
Tulip Breaking Virus
Transmitted by aphids, this viral condition results in blotchy, streaked or mottled tulip petals and leaves that appear silver or gray-ish. Growth may be stunted or slightly delayed, but tulips will not likely die from the disease. Double flowered varieties are more susceptible to ‘breaking’ than single flower varieties.
How to Identify
Look for irregular stripes, streaks, or flames, particularly on darker pigmented tulips. Leaves may be streaked with yellow or silver-gray. Stems may appear weak or wilted.
How to Prevent
Control aphid populations with manual hose spraying or horticultural oil application. Since some varieties with multi-color features are often derived from plants with viral hereditary, do not plant multicolor tulips in the same beds as solid varieties.
How to Treat
Dig up and dispose of tulips you suspect are infected with breaking virus, as the disease can be spread easily to other plants by aphids.
Tobacco Necrosis
Transmitted by a fungus in the brassicae family, tobacco necrosis will cause abnormal colors and streaking on your tulips’ petals. It may present with yellow to light green spots on young leaves, but it can attack all parts of the plant. It is often difficult to diagnose since many tulips are bred and prized for multicolor features.
How to Identify
Look for signs of tobacco necrosis in the leaves first. Mottled or chlorotic leaf color, stunted growth, and occasionally death can be the results of this disease. The bulbs will likely be sterile with no bulblets. Bulbs may have dead spots or streaks.
How to Prevent
If you’d like to plant multicolor tulips, purchase only from a reputable grower and check to make sure they are guaranteed virus free. Choose virus-resistant cultivars if you have had virus problems in the past. Do not plant near potatoes, as they are also predisposed to necrotic virus infection.
How to Treat
Tobacco necrosis is not fatal unless it becomes systemic. Plants that are unattractive or appear to be suffering should be removed from the ground and disposed of. Others can be left in place and monitored carefully for signs of advanced disease.
Tobacco Rattle
This pathogenic virus has a lot of hosts, including tulips. It is spread mechanically through the use of unsanitized tools or transmitted industrially through infected rootstock. Symptoms include ring spots, wavy patterns, and/or mottled blotches on leaves.
How to Identify
Leaves might have wavy, blotchy, or mosaic patterns and may be slightly deformed. Discoloration will be easier to spot in colder months.
How to Prevent
Choose tulips that claim resistance to viral conditions. Disinfect tools frequently to discourage mechanical transfer of the disease. Do not plant tulips in soil that has recently had a tobacco rattle outbreak.
How to Treat
Affected leaves can be pruned off to prevent spread. If the virus is present above ground, rather than below, this may be enough to stave off further infection. If roots are infected, remove the entire bulb and destroy.
Final Thoughts
Tulip growers who are new to the game can expect a few years of trial and error before getting things right. While your early priorities will focus on getting the spacing, timing, depth, and irrigation requirements down, you will likely have a run-in with disease at some point in your tulip journey, especially if you treat your tulips as perennials that will come back each season.
Keep your eyes open for symptoms like streaked or discolored leaves, irregular growth, weak stem structure and gray or brown spots to indicate the presence of disease. Then use your newly acquired diagnostic skills to determine what might be ailing them.
Since tulip disease symptoms are all pretty similar, it can be difficult to determine the exact pathogen, and that’s okay. What’s most important is that you take action to prevent further spread. Removal and disposal of infected plants (and their bulbs) is almost always going to be the safest approach to dealing with an outbreak. When in doubt, throw it out.
