4.1 Pestsanddiseases. 5 Cultivation.Dahlias are members of the Asteraceae (synonym name: Compositae) family of dicotyledonous plants,[4] its relatives include the sunflower, daisy, chrysanthemum, and zinnia. To deter slugs and snails, keep the soil surface as dry as possible. In damp weather, patrol daily (morning and/or evening) to gather and destroy these slimy beasts. You can also protect young plants with an organic slug repellent such as Sluggo. common-dahlia-pests-and-diseases2.jpg. Key to DahliaPests & Diseases. Home About DahliasPests & Diseases. As shown in the photo, dahlias attract insects, some of which are harmful to the dahlia. Dahlias are also subject to several diseases which are described below. Among the most common dahliadiseases are those caused by fungi, such as powdery mildew and gray mold. Dahlia flower pests tend to reflect the sap drinking forms but can also encompass leaf eaters such as a wide array of caterpillars and larvae. Dahlias are beautiful flowers, but there are many pests that love to try to ruin even the most perfect flower gardens.11 Lavender Pests & Diseases To Watch For This Season. Lavender is an extremely hardy plant. They fall victim to few pests, and very few diseases. Although dahlias can get different diseases, often the issue is pest damage that can be resolved by taking care of the pests by spraying with an insect spray related to the plant issue. Although virus can occur, virus is not common and your entire crop will not suddenly all have a virus. DahliaPestsAndDiseases. Verticillium Wilt Dahlia. Dahlia Plant Disease Identification.Understanding DahliaDiseases & Dahlia Viruses. Common Diseases of Dahlia Plants and How to Control Them. Foliar Spray. How to prevent diseases in dahlias. Many dahliadiseases can be combated by maintaining good plant health and using proper cultural practices.Bad practices can attract diseases or leave plants stressed, which puts them at more risk of succumbing to dahliapestsanddiseases. Pests love dahlias, making a tasty snack out of your vivid, stunning blooms. Learn which pests to watch for and how to control them at Gardener’s Path. Dahlias are among the most vibrant and rewarding flowering plants, but they are also prone to a variety of pestsanddiseases.DahliaDisease Prevention Tips. Preventing disease is often easier and more effective than treating it after the fact.