Lilies belong to a range of flowers that come in a variety of shapes, sizes and colors. The flowers are often brightly colored, with darker specks or spots along the petals, and grow well under warm, moist conditions. However, if the lily begins to turn brown, gardeners should take note, as there is a problem affecting the lily's health.
Lily Mosaic Disease
Lily mosaic disease is spread by aphids, according to the Ohio State University website. This disease causes a yellow or brown streaking or mottling of the leaves of the lily, followed by the leaves becoming misshapen or deformed. Severely affected lilies may be unable to produce blossoms. Mosaic disease is a virus, which means that it is not curable. Remove and destroy infected lilies to stop the disease from spreading and clean all garden tools before using them.
Anthracnose on Lilies
Anthracnose is a fungal disease that affects numerous plants, including lilies like the convallaria, or lily-of-the-valley. Anthracnose causes brown spots to appear on the leaves of the lily; according to the University of Illinois Extension website, these spots sometimes have purplish margins. Anthracnose weakens the lily and has the potential to reduce its ability to produce flowers. Control anthracnose by removing severely affected lilies and applying a fungicide to the garden to control the spread of the disease.
Botrytis Blight of Lilies
Botrytis blight, according to the Ohio State University website, causes orange-brown spots to appear on the leaves and stem of the lily; the spots later merge as the disease spreads through the plant. Once the blight reaches the flowers, the flowers themselves decay and die. The brown spots eventually turn into a grayish mold on the lily plant. Fungicide helps control the disease, and infected lily plants should be given water and fertilizer sparingly to prevent the disease from spreading.
Excess fertilizer has the potential to cause lilies to turn brown; the salt in the fertilizer builds up in the soil and dries out the lily, even when it receives water. This leads to a chemical burn on the leaves, especially at the tips. Similarly, dehydration of lilies can lead to problems with browning; soil that becomes too dry stops the lily from taking in nutrients and starts to damage the health of the lily.