No abstract

The incidence of Armillaria on small woody plants, small woody debris, and root fragments was estimated in red pine (Pinus resinosa Ait.) stands in northeastern Minnesota. Soil core samples 10 cm in diameter, and extending to a depth of either 16 or 25 cm, were collected from 13 stands belonging to three age-classes. Half of the youngest stands had been treated using herbicide. Mycelial fans or rhizomorphs of Armillaria were observed on 13% of the small woody plants and isolated from 8% of them. Including small woody debris and root fragments, 38% of 0–16 cm deep samples had Armillaria. Armillaria was observed on 3% and isolated from 1% of individual substrate units from 0 to 25 cm deep samples. Within a single stand, 0%–67% of the samples and 0%–9% of the individual units had evidence of Armillaria. All but one isolate were Armillaria ostoyae (Romagn.) Herink. Herbicide-treated and untreated red pine stands had similar Armillaria incidence, and there was a trend of incidence inversely related to stand age-class. Large numbers of small woody plants, woody debris, and root fragments were found in red pine stands; varying percentages of these substrates were contributing to the survival of Armillaria and could also be serving as sources of root disease inoculum.

No abstract

In 2019, Cactodera milleri cysts were discovered from soil samples collected from a Chenopodium quinoa field, located in Mosca, Alamosa county, Colorado, USA. Approximately 200 lemon shaped cysts and several hundred juveniles were recovered from the affected quinoa plants. The same species was also identified from several counties in Minnesota from samples submitted over the years by the Minnesota Department of Agriculture as part of the Animal and Plant Health Inspection Service (APHIS) efforts to survey states for the presence of Pale Potato Cyst Nematode. The cysts and juveniles (J2) were recovered from soil samples through sieving and Baermann funnel extraction. The nematode species was identified by both morphological and molecular means as Cactodera milleri (Graney and Bird, 1990). To our knowledge this represents the first report of Cactodera milleri from Colorado and Minnesota.

Damage and mortality data are collected as part of the US Forest Service, Forest Inventory and Analysis (FIA) ongoing assessments of the nation's timberlands. The usefulness and value of FIA tree data in assessing historical levels of oak decline and oak mortality were investigatedfor seven Midwestern states. The data were collected during two periodic inventories conducted between the early 1970s and the mid-1990s. One-tenth to one-third of the oak trees had decline-associated damage in a given inventory, but no trends over time were apparent across the states. Thepercentages of dead trees ranged from less than 1 to 11 across all inventories and states; mortality was higher in the late inventory than the early inventory for all states. This is the first reported attempt to quantify oak decline across the Midwestern Region and it was accomplished using FIA tree data. The major concerns of the approach used are the subjective nature of the damage codes used to tabulate declining oaks and the inconsistencies and inherent subjectivities in the FIA recorded codes. The major drawback for non-FIA researchers is the time required to understand the intricacies of the FIA system.