Tulip growing and care - diseases and physiological disorders to guard against

Season and cycle for Tulips

In hilly areas Tulips are planted in October- November and flowering takes place in early February. But some times flowering occurs in December also, it depends on cultivars and time of planting. Tulips prefer cool dry climate during their growth and flowering. High rainfall and humidity is a limiting factor in tulip cultivation. Generally tulips take six months from bulb planting to harvesting.

Main growing period for Tulip cultivation in hills is October –November. Bulbs are lifted in March–April. In Tulips the mother bulb dies after flowering and it regrows annually by the formation of one or more new daughter bulbs. The largest bulbs flowers in the next season. Smaller bulblets require 3-4 years to attain the flowering size.

Tulip needs moisture in early planting to initiate growth and require frequent watering during the period of growth up to and through flowering, until the leaves begins to dry. After rouging, deheading is beneficial for disease prevention and yield improvement. It has been found that competition between weeds and crops result in early senescence of plant and reduction in size of daughter bulbs, which ultimately produce fewer bulbs of flowering size.

Pests, diseases and physiological disorders affecting Tulip flowers and their growth

Tulips are attacked by Nematodes, Aphids, and Mites. Nematodes attack buds, leaves and plant tips. Stem nematode attack bulbs, which become soft, discoloured. Stems become split and bent resulted in premature plant mortality. Flowers become green streaked or poorly coloured.

Aphids (Dysaphis tulipae): These are the most common aphids attacking Tulip. They suck the sap of emerging shoots and the quality of the flower becomes poor. Spraying of insecticides at regular interval is recommended.

Another mite attacking the bulbs as secondary host is the bulb mite (Rhizoglyphus spp.). After attack, internal tissues of bulbs become dry and powdery. Soil sterilization, bulb dips and drenches and the use of systemic acaricidal granules (like Thimet 10-G or Phorat) are used to control the insects.

Diseases affecting Tulips

Tulips are mostly infected with fungal diseases like Fusarium bulb rot (Fusarium oxysporum f.sp. tulipae), Tulip fire (Botrytis Tulipae) and other viral diseases.

Fusarium is very serious disease which causes heavy loss to plant. Fusarium bulb rot is also called sour rot due to the smell of infected bulbs. Infected bulbs show large brown patches on outer fleshy scale. It also produces gum, which is a sticky liquid; it later becomes darker and produces sour smell. Field planted crops show early senescence and shoots become purple. The fungus persists in the soil for many years, without any host plants.

Control measures include early harvesting of bulb when tunic has become papery. Dip the bulbs in systemic insecticides immediately after harvesting.

Tulip fire is another major fungal disease infecting shoots and leafs. Infected leaves do not open, patches of severe leaf spotting occurs, which leads to loss of leaf area and finally flowers .Disease spread from infected mother bulb to daughter bulbs. Daughter bulbs bear small black patches under the tunic. The fungus is very persistent, remaining in the soil and on the withered scales of the old bulb.

Several measures can be adopted to check the spread of disease like removal of infected bulb along with adjoining soil, dusting the bulbs with sulphur powder and soaking the bulbs in systemic fungicide before planting. Timely removal of flower in the field is also helpful to control the disease.

At least 13 viruses are known to infect Tulip. The most common ‘Tulip Breaking Viruses' produce the unique and much prized colours on Tulip Perianths. Earlier it was considered natural but later it was declared virus infected. The vector of Tulip breaking viruses was identified as aphids. The general method of controlling virus disease is to restrict their spread. Spray of insecticides against the aphid. Rouging of infected plants and use of virus-free or virus tested mother stock.

There are three most common physiological disorders affecting the Tulip flowers and bulbs. These are called Blasting disorder, Topple and Chalking.

Blasting in Tulip (different from ‘bud necrosis’) is a black or brown wet rot of the flower and it starts when the bulb is in store with no external symptoms. This disorder may be due to accumulation of ethylene in store which is released by Fusarium infected bulbs. They deform the flower.

In topple disorder of Tulip; stems collapse at the time of flowering or after picking, so that flowers hang down. It has been due to the deficiency of calcium and high atmospheric humidity. Spray of dilute calcium nitrate solution can reduce the losses.

Another physiological disorder in Tulip is chalking. Bulbs become dry and hard in storage. Scales are white, opaque and chalk like when broken. This is associated with mechanical or sun scalds injury during lifting and aggravated by poor ventilation and high atmospheric humidity in store.