![]() ![]() ![]() Sanitation is the most important factor in managing plant disease. These open to release rust-colored spores. Rust disease leads to small, yellow swellings on the leaves or stems. Plants with Rhizoctonia root rot have reddish-brown lesions at the base of the stem. The cortex of the root (outer tissue) can be easily separated, leaving behind the thread-like stele. Plants affected by Pythium root rot have roots that are dark brown. Wilting is usually the first sign of root rots. Powdery mildew is easily identified by a white fungal growth that appears on either surface of lower leaves, as well as on the stems of some cultivars. Plants affected by downy mildew may fail to flower. The undersides of leaves will be covered by a gray to white fungus, and yellow areas will appear on the upper sides of the leaves. Petals affected by botrytis blight will turn brown and be covered with gray fungal growth.ĭowny mildew leads to stunted plants with leaves that curl downward. Leaves may die, and anthracnose may lead to the plant’s death if stems are girdled by lesions. Symptoms of anthracnose include yellow spots on leaves and stems these spots turn white with brown borders. Correct diagnosis of the disease is important for making management decisions. Common disease problems in snapdragons include anthracnose, botrytis blight, rust, powdery mildew, downy mildew, and root rots. High humidity, overhead watering, and plant debris may lead to increases in disease incidence. Potentially useful herbicides include Dacthal, Fusilade, Treflan, metoclachor, Poast, and Acclaim. A successful weed-management program uses cultural practices, such as cultivation and mulching, or a combination of cultural and chemical measures, taking into consideration labor costs and the cost and availability of materials. Weeds compete for water, nutrients, and light, which results in reduced flower yield and increased threat of serious insect and disease problems. ![]() Plants should be spaced 4–12 inches apart. Snapdragons perform well in full sun to partial shade. Sow 8–10 weeks before the last frost in your area if growing outside. If desired, pinch back to 1½–2 inches when the seedlings are about 3–4 inches tall to encourage branching. Transplant to packs or larger containers when the first true leaves appear, approximately 3–4 weeks after sowing. Bottom-water or mist lightly to avoid covering the seed with displaced soil. Light is required for germination, but a fine layer of vermiculite covering the seeds can maintain moisture levels and prevent algae growth. Snapdragons are annuals, and they perform well in sun to part shade in cooler parts of the year. Flower growers must consider seasonal timing and choose cultivars from appropriate groups. Group I cultivars are considered the winter-flowering snapdragons, performing with short days and low light Group II flower in late winter to early spring, with increasing day length and temperatures Group III consist of spring-flowering varieties and Group IV flower under high light intensities, long days, and night temperatures above 60✯ (16✬). Snapdragons are organized into four different groups (I–IV) based upon cultivars’ vegetative and reproductive responses to seasonal temperatures and photoperiod. They are easy to grow and come in a wide variety of colors. However, many consumers and florists prefer the more casual look of field-grown stems. Most of the snapdragon stems in flower shops are grown in greenhouses under carefully controlled conditions to provide long, straight stems. The diverse flower colors of the snapdragon’s tall spikes allow florists and consumers numerous design options. Up to 15 flowers appear close together along the stem, which measures up to 3 feet in length when cut. They are tubular with rounded upper and lower lips and can be single, double, or open-faced (“butterfly”) without a lip. Antirrhinum is Greek for “like” and “nose” in reference to the flower’s shape. The snapdragon (Antirrhinum majus) is a member of the Scrophulariaceae family. ![]()
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