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Greenhouse - Hyacinth

( Originally Published 1920 )

Cultural Considerations. In forcing (fig. 57, a) hyacinths it is important that they start with a well developed root system. Otherwise the culture is the same as for narcissus (see p. 287).


The few diseases which hyacinths are subject to are serious. Most of these, no doubt, have been brought in with imported bulbs.


Cause, physiological.

Symptoms. This trouble is characterized by the formation of pure white gum pockets between the epidermis and lower tissue. In this case the starch apparently becomes replaced by gum through a process of degeneration. The gum bearing cells often enlarge abnormally. The true cause of this trouble is unknown, but it is generally attributed to improper culture.


Caused by Bacillus hyacinthi septicus Heinz.

This disease has been studied by Heinz. Its presence in this country is unknown. Affected bulbs become soft rotted but remain white.


Caused by Pseudomonas hyacinthi (Wak.) Sm.

Symptoms. This disease as described by Smith t and others is characterized as follows: Early infection becomes apparent as water soaked stripes, soon followed by a yellowing then browning and dying of the affected tissue. The water soaked stripes soon spread all over the foliage, and the accompanying symptoms are the same as previously mentioned. The stripes usually start at the apex of the leaves. Frequently, the stripe runs down the entire length of the foliage while both margins remain green. On the flower stalks the disease is also manifested as a water soaked spot followed by the characteristic browning and shriveling. Infection on the bulb is at first confined to the vascular bundles the latter of which become yellow and gorged with slime. The disease soon spreads, invading and destroying the scales, the latter becoming yellow and soggy. Numerous other invading organisms often enter and help to complete the decay and the disorganization of the bulb. Often bulbs are attacked on one side only, in which case the growth of the foliage is also one sided, curved, and bends over towards the diseased side (fig. 57, b to h.).

The Organism. Pseudomonas hyacinthi is a medium sized rod, rounded at both ends, and is actively motile by means of one long polar flagellum (fig. 57, i.). It is non-sporiferous, produces no gas, and liquefies gelatin slowly.

Control. It is fortunate that the disease has not as yet proved serious in the United States. It is a very important disease in the Netherlands, and its introduction with imported bulbs should be guarded against by growers in the United States.

Crown Prince of Sweden

In Holland the disease is kept in check by the destruction of diseased plants. Diseased bulbs should never be planted since they will surely introduce the disease in new localities. Spraying in this case will be of no benefit.


Caused by Dictyuchus monosporus Seitg.

Symptoms. The above fungus causes a serious damping off, the symptoms of which resemble those of other plants. Dictyuchus monosporus is the only one of the genus SaprolginiaceŠ which is reported by Halsted as being parasitic on plants.

The Organism. The sporangia are clavate. The swarm spores become walled within the sporangium and emerge singly through its lateral walls. For methods of control soil sterilization is recommended (see pp. 32-43).


Caused by Rosellinia massinkii Sacc.

This fungus is reported by Halsted as thriving on hyacinth bulbs. However, the nature of the injury is not clearly stated by him.

The Organism. The fungus produces dark brown, elliptical spores. The asci are borne in globose or depressed dark colored perithecia.


Caused by Sclerotinia bulborum Rehn.

Symptoms. The disease is first manifested as yellow stripes or blotches on the leaves and bulbs. With the advance of the trouble, a velvety olive brown mold is formed on the surface of the spots. This growth is but the conidiophores and conidia of the causal fungus. The black sclerotia are developed on the rotted bulbs, and are found mostly within the outer scales. As the sclerotia winter over, they germinate by sending out slender stalks which bear apothecia and ascospores. The Botrytis form of spores is the most prevalent and is depended upon by the fungus to spread it quickly from plant to plant.

Control. Since numerous sclerotia are left in the soil with decayed bulbs, steam sterilization of the soil is recommended. Badly infected bulbs should be removed and destroyed by fire. Plenty of ventilation should be provided whenever possible.


Caused by Tylenchus dipsaci Kuhn.

Symptoms. This disease was first found in the United States by Byars on imported hyacinth .bulbs. It is prevalent in Europe where it attacks besides the hyacinth, clover, alfalfa, rye, oats, onion, potatoes, and numerous other wild and cultivated plants.

On the leaves, the nematode produces characteristic distortions and yellow to brown longitudinal discolorations. At the end of the growing season, the parasite migrates from the leaves to the scales of the bulbs. Diseased scales become discolored, so that when one cuts through an infected bulb, one or more yellow characteristic rings become very apparent.

The Organism. The adult worm is barely perceptible to the naked eye. It may, however, be readily seen with a magnifying hand lens. Each female produces numerous eggs which hatch into larvae, the latter of which reach maturity quickly. This means that several generations are produced in one season. Control. The disease is carried with infected bulbs. The latter should therefore be discarded and only healthy ones used.

GRAPE HYACINTH (Muscari botryoides)

Cultural Considerations. As soon as the bulbs are brought in the house, they should be given the benefit of the full light, and a low temperature. Neglect in this direction will result in spindly weak plants.


This plants is apparently very hardy. There are but two fungi recorded on this host :

Uromyces scillarum (Grey.) Wint., Ustilago vaillantii Tul.

HYDRANGEA (Hydrangea hortensis);

Cultural Considerations. Hydrangeas are valuable because of their adaptability to forcing for the Easter trade. Plants should be brought in the early part of January and freed from all old and dead leaves. The beginning temperature should be about 45 degrees F. and after two weeks it should be raised ten more degrees. To force them to flower the temperature is raised to 65 degrees. Ten days before Easter the blooming plants are given a temperature of 50 to 55 degrees. This hardens the blossoms and gives them better keeping qualities. During active growth they need plenty of ventilation, sunlight, and water, and frequent syringing.


Hydrangeas are very hardy plants. They are subject to but few diseases, which are of little importance.


Caused by Pucciniastrum hydrangea (B. and C.) Arth.

Rust is a serious disease on hydrangeas. The uredinial and tetial stages of the causal organism are doing the damage. Selby* was perhaps the first to have observed the rust, although little more has been added to our knowledge of it or of methods of control.

The Organism. As far as is known Pucciniastrum hydrangea has only two spore stages, the uredo and teliospores. The uredinia are found scattered mostly on the under side of the leaf, their color dark yellow to pale yellow. The peridium is delicate, the cells are small, while the walls are thin throughout. The ostiolar cells are somewhat elongated, and slightly pointed, the spores are broadly elliptical to ovate; the cell wall is thin and warty. The telia are usually found on the lower part of the leaf in small angular groups, that are rather flat and reddish brown in color. Spores are formed in a single layer within the epidermal cells or immediately beneath it; the cell wall is thin, and a dark, cinnamon brown in color. No methods of control are known. The disease may be introduced into the greenhouse with infected plants.


Caused by Phyllosticta hydrangea E. and E.

The disease is characterized by large, rusty, brown spots occurring on the leaves, especially at the edges. The disease is often so severe that it is necessary to cut off the top of the plant. Upon examination of the affected leaves, numerous minute, black pycnidia will be found scattered throughout. The conidia are oblong, hyaline, and one celled, and generally ooze out as minute creamy tendrils. The disease may be kept in check by spraying with a standard fungicide.

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