Showing posts with label grapes. Show all posts
Showing posts with label grapes. Show all posts

Monday, May 23, 2011

Making a Stink About Bugs

The introduction of new insect pests damaging to grapes is an ongoing threat for California’s grape growers.  Light brown apple (LBAM) and European grapevine (EGVM) moths are two recent examples of introduced insects the presence of which has been very costly to growers.  Although safe and effective conventional and organic control methods are available to manage moths, these particular insects are considered ‘quarantine’ pests, so extra special measures must be taken in the vineyard and throughout the fruit distribution and processing network.  Quarantine pests are a particular concern for the trade of fresh fruits, such as table grapes, due to import restrictions in some domestic and international markets.  Exactly how these insects made it to California is not presently known, but past insect introductions have come from contaminated plants and plant products.  Thus, it is critically important that everyone recognize the potential danger of violating plant protection and quarantine regulations.
Just as grape growers learn they have made excellent progress toward eradicating EGVM, officials are expressing concern over a new exotic insect pest, the brown marmorated stink bug (BMSB).  The BMSB is now found in 33 States.  Although not established in California, it has been identified in Los Angeles and Solano Counties.  BMBS can fly, but they primarily move into new areas by hitchhiking on vehicles and equipment.  Native to Asia, its thought that BMSB arrived in packing crates shipped to the Eastern US.  It has a large host range that includes grapes and many of the fruits and vegetables grown in California.  Damage can be substantial when BMSB populations are not identified early and managed appropriately. Apple growers in the Mid-Atlantic States have reported losses of $37 million representing 18% of their fresh apple market.  Growers and wineries are also concerned that the “stink” from any bugs accidentally crushed in wine or juice grapes could taint the product with off flavors. This insect should concern homeowners as well, since people in the Mid-Atlantic States have reported large populations of BMBS overwintering in their homes and becoming a nuisance.  
BMSBs resemble some other California stinkbugs such as the rough stink bug, a beneficial predator of other insects.  If you think you’ve found a BMSB, or any other odd or unique looking insect pest, you should collect it and bring it to your local university advisor, ag commissioner or state ag department entomologist for proper identification.  Early identification of invasive pests is critical for protecting California’s billion dollar agricultural industries.

You can learn more about the BMSB and current research here.

Thursday, May 19, 2011

Breeding New Pest Resistant Rootstocks for Grapes

With bloom well underway, grapevine breeders and geneticists, such as Peter Cousins, with the USDA’s Grape Genetics Research Unit, in Geneva, NY, are busy making crosses between pairs of vines having favorable traits.  Cousins is a rootstock breeder, so traits that interest him include resistance to root-knot nematodes, soil-borne pests whose feeding activities can cause extensive damage to grapevine roots, thereby weakening the vines and reducing yields.  Though Cousins, is based in NY, he is cultivating some advanced selections from his rootstock breeding program in a vineyard at the Kearney Agricultural Research and Extension Center in Parlier, California.  By growing the vines at Kearney, Cousins can assess their performance in the San Joaquin Valley, one of the most important grape-growing regions in the world.  Vines that maintain their nematode resistance, grow well, and are easily propagated, may eventually be released as commercial rootstocks, and serve as a genetic resource for future crosses aimed at further strengthening their nematode resistance by incorporating as many resistance mechanisms for resistance as possible.
Some wild grapevine species have unique nematode resistance mechanisms, and are thus used as parents in rootstock breeding.  Cousin’s goal is to incorporate as many different forms of resistance as possible into new rootstocks, so some advanced selections are complex hybrids of several species.  Wild grapevines, and their hybrids, are dioecious; invididual vines bear clusters of either male or female flowers.  Dioecious vines are relatively easy to cross as the flowers do not have to be emasculated; to prevent unwanted crosses, he simply encloses female flower clusters in paper bags prior to bloom. 
As bloom approaches, he periodically he taps on the bags, listening for the rattle of detached petals that signals the blossoms are ready to be pollinated.  Properly prepared, pollen, which Cousins prepares by grinding flowers in a coffee mill, can be stored for a relatively long time, facilitating crosses between vines that might not flower at the same time.  To pollinate, the bags are removed, the appropriate pollen is slathered on with paint brush, and the cluster is labeled, and recovered with the bag.  Cousins will return in the summer, to extract the seeds from the fruit.  Seedlings will then be screened for nematode resistance, and the best selections may eventually end up returning to Parlier, to be evaluated alongside their parents.  To learn more about Dr. Cousin’s research program, and see his rootstock selection vineyard, plan to attend Grape Day at Kearney, August 18, 2011.