Anthurium abnormalities

Flower abnormalities

By the time Anthurium reaches the mature stage, several flower buds will have formed in the growing point. Typically, at least three buds are ready to open, meaning there is roughly half a year’s worth of production in the plant at that stage.

These young flower buds are highly sensitive to imbalances between the average daily temperature and the amount of light received. When high average daily temperatures above 25°C coincide with several weeks of comparatively low light, the resulting growth disruption can lead to spadix and flower abnormalities months later.

For more information, see the article on the effect of a high average daily temperature on Anthurium flower formation.

Droopy flowers

In Europe, we mainly see droopy Anthurium flowers in March and April. The symptoms are identical to those of flowers that droop when cut and left without water: the spathe is no longer firm and loses its gloss. Varietal sensitivity is a major factor in this phenomenon, and young plants are significantly more susceptible than mature ones. A high growth speed can also exacerbate the problem.

The best measures to prevent droopy flowers are:

• Maintain a moderate growth speed;
• Cut flowers only at full maturity;
• Leave freshly cut flowers in the greenhouse (under high relative humidity) for 24 hours before packing;
• Cut off a small piece of the stem 12–24 hours after the first cut.

Swollen flower buds

Swollen flower buds occur mainly in young plants (within the first six months after planting) grown under ‘rapid’ cultivation conditions. Because such plants are prone to heavy guttation in the morning, it is advisable to lower the target relative humidity by 5–10% and slightly reduce the temperature. Ensure relative humidity at night does not rise too high (RH <90%).

Warts or eruptions on the spathes

Varietal sensitivity is also a factor in this phenomenon. Low spathe temperature may lead to warts or eruptions on the spathes. Prevent low flower temperatures by using correct screen-gap control when opening the thermal screen in the morning.

Stuck buds and leaves

Flowers and leaves can become stuck in the sheath, resulting in damage or breakage. The underlying causes are usually one or a combination of:

• Low greenhouse relative humidity (RH <70%/MD >9.0);
• Low night-time relative humidity in winter, often caused by high temperatures of the floor-level heating pipe;
• Poor microclimate caused by an open crop stand (too few leaves or plants per m²) and/or dry surface layer of the substrate;
• Poor root quality;
• High electrical conductivity (EC >3.0) in the substrate.

In winter, the sheaths often become stiffer, and as growth speeds up in spring, the issue may reappear. The bud is held back by the rigid sheath.

Cork formation

Cork forms when nutrient solution enters young flower buds. As the solution evaporates, EC levels rise sharply, increasing osmotic pressure and damaging the young leaf bud tissue. Once the flower develops, this corky tissue becomes visible. This problem occurs with overhead watering (potted plants) and watering from below with the rainwater pipe (cut-flower cultivation). At the start of cut-flower cultivation, avoid supplying nutrient solution via the rainwater pipe during the first few months. After several months, the flower buds are high enough in the plant that water from the rainwater pipe no longer reaches them. During that first period, supply nutrients through the drip line. If a rainwater pipe is the only available irrigation system, use lower water pressure. Watering in the evening also reduces this problem, as the buds then dry slowly. In potted plant cultivation, follow overhead watering with rinsing using clean water plus a suitable wetting agent and/or Epsom salts. Water very early in the morning so that the buds have partially dried before the sun accelerates the drying process.

Stuck spathes

If the spathe grows more slowly than the spadix, the spadix may be holding it back. Low relative humidity clearly exacerbates this problem. Stuck spathes will eventually release, but the spathe’s appearance will often be less attractive.

Brown spadices

Under sudden warm and humid conditions, certain varieties are susceptible to this problem. On hot summer days, when thunderstorms approach towards the end of the day and air vents are closed, the resulting warm, moist air creates ideal conditions for brown spadices. To prevent this, harvest the more sensitive varieties slightly earlier on such days, as mature flowers are much more prone to this phenomenon. Open the air vents again as soon as the weather allows.

Cup shape

Under rapid growth conditions, the spadix matures quickly and the spathe may not have enough time to unfold completely. This phenomenon is highly variety-dependent and occurs mostly in summer. Avoid high spathe temperatures (often caused by excessive radiation).