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Commercial Horticulture

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Floriculture

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Cut Flowers

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Warm Season Pests and Diseases [Image: Anthracnose on zinnia] [Image: Beetle damage on sunflower] Though the spring crops rarely have any problems except poor drainage, the rest of the warm season sees the same leaf spots and insect damage also seen on vegetables. Foliage diseases are not much of a problem in cuts because flowers are rarely affected and most of the leaves will be stripped off and discarded when the flowers are sorted. As summer sets in, insects will begin to affect sunflowers, celosias and snaps. The problems will continue through the fall. Scout for petal-eating beetles and aphids on the sunflowers. Aphids will deform and discolor the few top leaves that will be left on the stem. Spray a good basic insecticide when aphids are first sighted on the undersides of the leaves. The beetles will wait until the petals of the flower head unfold, then start removing the petals. Spray or try to harvest the flowers before they are damaged. Gladiolas are beloved by thrips, which stipple the leaves and cause the edges of the petals to have a burnt look. Give glads a regular preventive spray of Malathion, or use a systemic insecticide applied to the soil. Celosias and snaps are attacked by caterpillars as the weather warms. Either give the celosias and snaps a preventive spray of Bt or watch for the clouds of small brownish moths that will land on the celosias. Spray the moths with insecticide before they lay their eggs. Hand-stripping and washing every flower stem is much too time-consuming for commercial production.