Do not add wet paper towels or extra water to the bag. Place leaves inside a resealable plastic bag. The number of leaves to collect per hop plant depends on the sampling scheme:Ī sample collected from a single hop plant consists of four fully expanded leaves with attached petioles (stems). Concentrations of viruses and viroids are generally higher when plants are green and actively growing, and higher in petioles and main leaf veins, where virus particles are transported.
It is not necessary to use cutting tools for leaf collection.Always change your gloves before collecting samples from a different plant. It is highly recommended to use disposable gloves when taking samples from more than one plant.Our testing method is very sensitive, and so sap from an infected hop plant can compromise the test results of a healthy one. Label sample bag. Using a black or blue permanent marker, label a gallon-size resealable plastic bag with your sample identifier.Mark the plants selected for sampling until results are received as it may be necessary to re-sample and re-test. For example, plants may show leaf discoloration (e.g., yellowing, light-color speckles, rings, arcs) and/or growth distortions (twisted leaves, stunting, bines that fall off the strings, poor yield, etc.). Select and mark suspect hop plants. A suspect hop plant usually has atypical growth or performance.General guidelines on hop leaf sample collection If you suspect a virus or viroid problem on one or more plants in your hop yard, consider submitting a leaf sample for testing. Keep in mind that nutrient and water deficiencies can mimic viral symptoms and should be considered. Symptoms of viral infection may be obvious or subtle, or not visible at all. The expression of disease symptoms caused by viruses and viroids depends on many factors including hop cultivar, environmental conditions, and the pathogen present. In other cases, symptoms may be much more subtle or not evident. This hop plant was positive for American hop latent virus, hop latent virus, hop mosaic virus and hop stunt viroid, and shows dramatic discoloration. The perennial nature of hop and common methods of propagation contribute to the accumulation of these pathogens over time. Several of these pathogens are widespread in Michigan and mixed infections of multiple viruses and viroids in a single plant are frequently found.
Hops are known to host several viruses and viroids that potentially impact profitability by reducing yield, quality, and/or plant longevity. Sample fees for virus and viroid testing.General guidelines on hop leaf sample collection.