Tulips - Common Tulip Diseases
The overwhelming majority of diseases in tulips, as for other living things, are caused by bacteria, fungi and/or viruses. Combating them in the case of tulips, fortunately, is usually not a full-time occupation. Tulips tend to be hardy and disease resistant. There are a few common problems, though, that are worth watching out for.
Many start right at the bulb. Basal Rot, caused by Fusarium oxysporum, is a fungal growth that produces large, dark brown spots on the bulb. The bulb may also have a white or pink fungal growth. Even if the plant grows the flowers become deformed and the foliage will often die prematurely. Management is simple. Just avoid planting bulbs that have a white or pink fungus on them.
Blue Mold is another common disease of tulip bulbs. The disease is caused by the penicillium fungus and bulbs acquire a bluish tinge. The leaves may be reddish, while the roots may be powdery. Try to purchase bulbs that have been pre-treated for fungi. Propiconazole (Brand name: Banner) is useful for protecting plants from invasion.
Botrytis infects many plants, especially bulb types, and tulips are no exception. Botrytis tulipae, in particular (which sometimes goes by the name Blight or Fire), may produce stunted or deformed leaves. Dead spots on the foliage are often surrounded by dark green circles. The spots turn yellow and may have small black spots speckled within them. Buying fungicide-treated bulbs will help avoid that fate.
Treatment with chlorothalonil (Trade name Daconil), mancozeb (Dithane) or iprodione (Chipco) can keep healthy plants healthy. Layering coarse sand above the bulb when planting can also help prevent invasion.
Various types of pythium are another common invader. They produce a type of root rot. The bulbs will have soft gray spots with brown borders near the base. Roots may be slimy. Using chemically treated soil will help avoid the disease in the first place. Unfortunately, once infected, about the only method is to discard diseased plants. That helps keep it away from those not yet exposed.
Crown rot (also known as Southern Blight) is sometimes a problem. Caused by sclerotium rolfsii, it produces yellowed leaves and a fibrous rot on the bulb. Plants are typically stunted and will die prematurely. Fumigating the soil can help remove the condition, but often that will have to be accompanied by discarding the diseased cultivars.
A whole library full of viruses are around that can infect tulips and, being viruses, new ones evolve all the time. Tobacco mosaic and cucumber mosaic are only two out of thousands. At a certain stage, the leaves will become mottled with yellow flecks that can spread into stripes. Petals will become distorted and break off prematurely.
Viruses can be caused by invaders in the soil or spread by aphids. Keeping the insects at bay will help with prevention. Cuttings are another way to inadvertently spread the disease. In most cases, the only effective management is to discard the plant.
Keeping tulips healthy is easier than many other plants. They first evolved in the Central Asian regions where winters are cold, springs bring plentiful rain, and summers are hot and dry. That makes them hardy survivors. But a little help from gardeners is always appreciated.
