TULIP DISEASES




As garden plants go, tulips are among the most popular, best value and relatively disease free plants that you can buy. Unfortunately high volume production techniques and a tolerance to unsympathetic environmental conditions has seen a steady increase in pathogenic attack. Although thankfully its still quite rare to find diseased bulb stocks in the garden, there are more and more infected bulbs coming on the market place direct from the growers. The most common diseases you are likely to find are as follows.

TULIP GREY BULB ROT

Symptoms: The bulbs will either fail to emerge, or they will produce severely distorted shoots which will eventually wither and die. Below ground, the bulbs will turn grey and progressively drier as the rot develops, until only the roots and basal plate remain.

Cause: the fungus Rhizoctonia tuliparum. This will not only infect tulips but many other types of bulbs besides.

Control: Unfortunately there is no cure, but to prevent further infection you must remove and burn all the infected plants. Next you must removal of the surrounding soil which can be sterilized using Jeyes fluid or burning. Do not plant other bulbs in the same spot for at least five years in case of re-infection from dormant spores.

TULIP CROWN ROT

Symptoms: The bulbs will either fail completely of just to emerge. Any new growth that does appear will be severely distorted only to wither and die. The bulb itself will turn grey and dry up until only the roots and basal plate remain.
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Cause: A fungus known as Sclerotium delphinii which can lie dormant in the soil for many years. Infections usually occur on the stems near the soil surface. Although not widespread, it can cause serious damage, especially in moist, warm soils.

Control: Remove all affected foliage immediately and to prevent further infection you must remove and burn all infected plants and soil. Do not plant tulips in the same area for at least three years as this will discourage the build up of any further disease. Try planting later in the season to discourage the disease from developing. In milder climates it can be left as late as early January. Lift bulbs at the end of the season and dust with an anti-fungal sulphur powder..

TULIP FIRE

Symptoms: The bulbs should emerge but they will be showing withered, distorted foliage with pale coloured flecks. Sometimes the infection shows as a scorched appearance, soon followed by a fuzzy mould. The plants will often fail to mature or flower but if the flowers do open, the petals will show bleached spots. The flower stems will also be weak and prone to collapse.

Cause: the fungus Botrytis tulipae. The fungal spores overwinter in the soil on infected bulbs. Once the fungus displays its fruiting bodies, new spores are spread to other plants by air or water splash.

Control: Remove all affected foliage immediately and to prevent further infection you must remove and burn all infected plants and soil. Do not plant tulips in the same area for at least three years as this will discourage the build up of any further disease. Try planting later in the season to discourage the disease from developing. In milder climates it can be left as late as early January. Lift bulbs at the end of the season and dust with an anti-fungal sulphur powder.
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TULIP BREAKING VIRUS
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Symptoms: This virus causes colour breaking on the petals of pink, purple and red flowered cultivars although yellow and white coloured varieties are not affected. This 'breaking' can take the form of conspicuous white or yellow streaking across the petals or streaking of a darker shade compared to the original colour. Sometime you may see a combination of the two effects. Occasionally you may come across mottling or striping of the plants leaves.
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Cause: This virus is transferred from plant to plant by the following aphids - Myzus persicae Macrosiphum euphorbiae, and Aphis fabae. As the aphid bites into an infected plant, small amounts of the virus are left in it mouthparts. When the aphid moves to another host the virus enters the plant's vascular system when the aphid once again starts to feed.

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