Brian Smith, UWRF
Photo 1: Lydecker® BlackIce ™= Plum. 'Oka' ( Prunus besseyi x P. salicina) x Z's Blue Giant (P. sal.).
Emily Dusek, University of Wisconsin River Falls
Plums have long been regarded as a fruit that can be grown in the Midwest, but the size and quality has never measured up to that of California's plums. Well we Midwesterners need not lament anymore because the new Lydecker/BlackIce™ Plum (bred by Dr. Brian Smith from University of Wisconsin-River Falls) exhibits many of the characteristics of Californian Plums all while being a winter-hardy plum!
This was achieved because the BlackIce™ was bred from a flavorful Californian plum (Z's Blue Giant) and a winter hardy plum (Oka). With this combination of genes, the BlackIce™ has a dark purpley-black tender skin, with rich juicy red flesh on the inside, and free-stone pit that does not stick to the flesh. All while being winter-hardy to as low as -35 ºF (Zone 3b) and ripening 2 to 3 weeks earlier then any other large quality plum for the Midwest!
Brian Smith, UWRFPhoto 2: Lydecker® BlackIce™ Plum. 'Oka' ( Prunus besseyi x P. salicina) x Z's Blue Giant (P. sal.).
In addition to an earlier ripening period and larger sized fruit (5cm x 5cm), the BlackIce™ exhibits many other positive characteristics, such as being naturally semi-dwarf in size and only growing to about 10' tall and 8' wide. It also has a weepy growth habit, which gives the BlackIce™ an interesting appearance in the winter and spring--but its main attribute is its ability to produce California-like plums in the Midwest.
To get the optimum yield of these tasty plums, it is necessary to plant another cultivar of compatible genetic background with the same bloom-time so cross-pollination can occur. This is because plum trees are self-infertile, and for successful pollination to take place there needs to be another plum within 50 feet. The preferred pollinator for BlackIce™ is Toka, but if there is a late bloom season for the BlackIce™ either 'Compass' or 'Alderman' plums will suffice.
it is very important not to apply any insecticide to your trees while they are blooming because otherwise the bees will not be able to carry the pollen from one tree to the other to pollinate your flowers so they can develop into fruit!
When growing fruit, it is crucial to monitor for pests. In regards to insects, the BlackIce's™ problems include scale, plum curculio, cat-facing insects and peach tree borer, the best control for any pest is always sanitation. So remember to remove all of your dead plant debris from the ground! In addition to good sanitation, it is also necessary to have a spraying regime in place to prevent and control all insects. The BlackIce™'s disease susceptibility is average to above average. It is still moderately susceptible to brown rot and black knot, which are fungal diseases that are also best controlled by the removal of all plant debris from the ground, and pruning off of any infected areas. And fungicide applications should be done just before bloom/early bloom, mid-bloom, and late bloom. Luckily, BlackIce™ is more tolerant than its Japanese-American hybrid counterparts to bacterial spot.
Once these simple control measures are in place, the enjoyment you receive from planting, growing, and eating these sweet plums will be boundless. For with these multiple attributes of color, and firmness combined with the winter hardiness necessary to survive harsh winters and short-growing seasons it is evident that BlackIce™ has the potential to bring the fresh taste of California to our very own backyards.
Editor's note: A good article on cat-facing insects can be accessed at the Utah State University Cooperative Extension.
Emily Dusek graduated with an A.S in Horticulture from Century College in 2009. She is currently attending University of Wisconsin-River Falls to parlay her A.S. into a Bachelor's of Science. She has also received invaluable hands-on lessons working at Farrill's Sunrise Nursery in Hudson, Wisconsin. Emily first got into horticulture as just a baby; she has been told her first birthday present was a mini wheelbarrow and watering can!