Agriculture-Agricultural Research Service Research Articles

Evaluating a Deer-Targeted Acaricide Applicator for Area-Wide Suppression of Blacklegged Ticks, Ixodes scapularis (Acari: Ixodidae), in Rhode Island

Over a 5-year period, September 1997 through May 2002, as many as 25 U.S. Department of Agriculture-Agricultural Research Service "4-Poster" acaricide applicators were distributed in areas of high deer activity throughout a 518-hectare area in a rural Rhode Island community. Corn consumption and acaricide levels for each device were monitored weekly during each treatment season to assess the degree of deer use. The efficacy of acaricide treatment was determined by comparing relative blacklegged tick (Ixodes scapularis) densities in the 4-Poster treatment site to a separate, similar-sized nontreatment area. The tendency of white-tailed deer to use the 4-Poster was variable temporally, and appeared to be largely dependent on the availability of alternative food sources. Total corn consumption was nearly fourfold lower during large oak masting years when compared with no/low mast years. Moreover, habitat characteristics, such as the presence of maintained hay lands consisting of alfalfa and clover, also appeared to influence the frequency and amount of 4-Poster use. After 2 years of adequate treatment (nearly 12,000 kg of corn consumed), we achieved nearly 50% control of nymphal blacklegged ticks within the treatment site compared with tick abundance levels in the nontreated area. Moreover, that level of tick control was maintained for 1 year after removal of the 4-Poster devices but began to wane 2 years after treatment ended.

SPICATIC ACID: A 4-CAROXYGENTISIC ACID FROM A GENTIANA SPICATA EXTRACT WITH POTENTIAL HEPATOPROTECTIVE ACTIVITY

Filariasis and Dengue Fever are two mosquito-borne diseases threatening French Polynesia. The potential vectors for the transmission of these illnesses are Aedes aegypti (L.), the Yellow Fever mosquito, and A. polynesiensis Marks. A research program financed by the Ministry of Health of French Polynesia, the Establishment for Prevention and the Laboratory of Ecophysiology and Biotechnology of Halophytes and Marine Algae was undertaken with the ultimate goal of developing improved insect repellents and lures for insect traps. This goal became even more urgent due to the threat of mosquito-borne diseases. Several natural products from terrestrial plants of French Polynesia were evaluated as spatial repellents against A. aegypti mosquitoes, using a triple cage-dual port olfactometer, and as topical repellents, using a cloth patch assay test with DEET as the positive control. The attraction of A. aegypti to L-lactic acid combined with the natural sample extracts was evaluated using the dual-port olfactometer. A total of 10 aromatic plant species have been collected by the Laboratory of Natural Products of the Institute Louis MalardA©, and these have yielded 10 Essential Oils. 4 more samples of essential oils originating from New Caledonia and Madagascar were also tested. The fine chemical composition of some repellent essential oils were determined by gas chromatography and gas chromatography coupled with Mass Spectrometry at MalardA© and at Montpellier. Their major volatile components are still to be tested and the preliminary results are presented. Bioassays were performed with Ae. aegypti mosquitoes at the U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS). This mosquito is the commonly accepted standard species for laboratory bioassays. Bioassays were conducted in randomized sample order and were distributed among the three cages of the olfactometer over three separate assay periods per day (approximately 08.00, 11.00, and 13.00 local time). Each sample was analyzed at least 3 times to improve the statistical precision of the results. The cloth patch repellency assays were conducted using 5-6 individuals to provide adequate precision of the duration and minimum effective dosage measures of the repellent efficacy.

Semiparametric geographically weighted response curves with application to site-specific agriculture

Lack of basic knowledge about spatial and treatment varying crop response to irrigation hinders irrigation management and economic analysis for site-specific agriculture. One model that has been postulated for relating crop-specific economic quantities to irrigation is a quadratic response curve of yield as a function of irrigation. Although this model has far reaching economic interpretations it does not account for spatial variation or possible nitrogen-irrigation interactions. To this end we propose a spatially treatment varying coefficient model that alleviates these limitations while providing measures of uncertainty for the estimated coefficient surfaces as well as other derived quantities of interest. The modeling framework we propose is of independent interest and can be used in many different applications. Finally, an example involving site-specific agricultural data from the U.S. Department of Agriculture-Agricultural Research Service demonstrates the applicability of this methodology.

Mosquito repellents from essential oils and crude extracts of plants of French Polynesia

Filariasis and Dengue Fever are two mosquito-borne diseases threatening French Polynesia. The potential vectors for transmission of these illnesses are Aedes aegypti (L.), the Yellow Fever mosquito, and Ae. polynesiensis Marks. A research program financed by the Ministry of Health of French Polynesia, the Establishment for Prevention and the Laboratory of Ecophysiology and Biotechnology of Halophytes and Marine Algae was undertaken with the ultimate goal of development of improved insect repellents and lures for insect traps. This goal is made more urgent by the threat of mosquito-borne diseases. Several natural products from terrestrial plants of French Polynesia were evaluated as spatial repellents against Ae. aegypti mosquitoes using a triple cage-dual port olfactometer and as topical repellents using a „cloth patch assay“ test with DEET as the positive control. In addition, the attraction of Ae. aegypti to L-lactic acid combined with the natural sample extracts were evaluated using the dual-port olfactometer. A total of 25 plant species have been collected by the Laboratory of Natural Products of the Institute Louis Malardé, and these have yielded 9 Essential Oils and 21 crude methanolic extracts. The fine chemical composition of some repellent essential oils were determined by gas chromatography and gas chromatography coupled with Mass Spectrometry at Malardé and at Montpellier. Their major volatile components were tested and the preliminary results are presented. Bioassays were performed with Ae. aegypti mosquitoes at the U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS). This mosquito is the commonly accepted standard species for laboratory bioassays. Bioassays were conducted in with randomized sample order and distributed among the three cages of the olfactometer over three separate assay periods per day (approximately 0800, 1100, and 1300 local time). Each sample was analyzed at least times to improve the statistical precision of the results. The cloth patch repellency assays were conducted using 5–6 individuals to provide adequate precision if the duration and minimum effective dosage measures of repellent efficacy.

Landscape complexity and soil moisture variation in south Georgia, USA, for remote sensing applications

Summary This research addressed the temporal and spatial variation of soil moisture (SM) in a heterogeneous landscape. The research objective was to investigate soil moisture variation in eight homogeneous 30 by 30 m plots, similar to the pixel size of a Landsat Thematic Mapper (TM) or Enhanced Thematic Mapper plus (ETM+) image. The plots were adjacent to eight stations of an in situ soil moisture network operated by the United States Department of Agriculture-Agriculture Research Service USDA-ARS in Tifton, GA. We also studied five adjacent agricultural fields to examine the effect of different landuses/land covers (LULC) (grass, orchard, peanuts, cotton and bare soil) on the temporal and spatial variation of soil moisture. Soil moisture field data were collected on eight occasions throughout 2005 and January 2006 to establish comparisons within and among eight homogeneous plots. Consistently throughout time, analysis of variance (ANOVA) showed high variation in the soil moisture behavior among the plots and high homogeneity in the soil moisture behavior within them. A precipitation analysis for the eight sampling dates throughout the year 2005 showed similar rainfall conditions for the eight study plots. Therefore, soil moisture variation among locations was explained by in situ local conditions. Temporal stability geostatistical analysis showed that soil moisture has high temporal stability within the small plots and that a single point reading can be used to monitor soil moisture status for the plot within a maximum 3% volume/volume (v/v) soil moisture variation. Similarly, t -statistic analysis showed that soil moisture status in the upper soil layer changes within 24 h. We found statistical differences in the soil moisture between the different LULC in the agricultural fields as well as statistical differences between these fields and the adjacent 30 by 30 m plots. From this analysis, it was demonstrated that spatial proximity is not enough to produce similar soil moisture, since t -test’s among adjacent plots with different LULCs showed significant differences. These results confirm that a remote sensing approach that considers homogeneous LULC landscape fragments can be used to identify landscape units of similar soil moisture behavior under heterogeneous landscapes. In addition, the in situ USDA-ARS network will serve better in remote sensing studies in which sensors with fine spatial resolution are evaluated. This study is a first step towards identifying landscape units that can be monitored using the single point reading of the USDA-ARS stations network.

Outcrossing in Florida Avocados as Measured Using Microsatellite Markers

Avocado (Persea americana Mill.) possesses a unique flowering mechanism, thought to promote out-crossing, in which the male and female parts of the perfect flower function at different time periods. Cultivars are classified as Flowering Type A, where flowers are functionally female the morning of one day and functionally male the afternoon of the next day, or Flowering Type B, where flowers are functionally female in the afternoon and functionally male the next morning. Avocado growers typically interplant cultivars of opposite flowering types to maximize yield. Recently, it has been hypothesized that 90% to 95% of avocado flowers are self-pollinated in southern Florida. However, this hypothesis does not address whether mature, marketable avocado fruit in Florida are the result of outcrossing. To determine whether avocado fruit in southern Florida result from self-pollination or outcrossing, fruit were harvested from a commercial orchard in Miami-Dade County, Florida, from a block consisting of two cultivars, Simmonds (Flowering Type A) and Tonnage (Flowering Type B), interplanted in approximately equal numbers. Seeds were germinated and the resulting progeny were genotyped using eight fully informative, microsatellite markers. Seventy-four percent of the ‘Simmonds’ progeny and 96% of the ‘Tonnage’ progeny were judged to be the result of cross-pollination, with an estimated overall outcrossing rate of 63% to 85% within this particular block of the orchard. Seedlings judged to be the result of cross-pollinations between ‘Simmonds’ and ‘Tonnage’ are being maintained at the U.S. Department of Agriculture-Agricultural Research Service, Subtropical Horticulture Research Station and are being evaluated for segregation of important agronomic and horticultural traits.

USDA-ARS Research on Practices Compatible with Organic Agriculture for Management of Plant-Parasitic Nematodes on Vegetable Crops

Abstract The market for organically grown fruits and vegetables has been increasing in recent years, and research is vital for obtaining optimal quality and yields in organic production systems. Scientists at the United States Department of Agriculture-Agricultural Research Service (USDA-ARS) are investigating methods for managing plant-parasitic nematodes on these crops, and studies that involve practices appropriate for organic vegetable production are reviewed in this paper. The projects summarized here focus primarily on suppression of root knot nematode species, including Meloidogyne arenaria (Neal) Chitwood, M. hapla Chitwood, M. incognita (Kofoid and White) Chitwood and M. javanica (Treub) Chitwood. Projects from Florida include investigations of plant growth-promoting rhizobacteria (PGPR) and chitin amendments for management of nematodes on pepper (Capsicum annuum L.), muskmelon (Cucumis melo L.), and tomato (Solanum lycopersicum L.). In South Carolina, research programs focus on the identificatio...

Perilipin regulates the thermogenic actions of norepinephrine in brown adipose tissue

In response to cold, norepinephrine (NE)-induced triacylglycerol hydrolysis (lipolysis) in adipocytes of brown adipose tissue (BAT) provides fatty acid substrates to mitochondria for heat generation (adaptive thermogenesis). NE-induced lipolysis is mediated by protein kinase A (PKA)-dependent phosphorylation of perilipin, a lipid droplet-associated protein that is the major regulator of lipolysis. We investigated the role of perilipin PKA phosphorylation in BAT NE-stimulated thermogenesis using a novel mouse model in which a mutant form of perilipin, lacking all six PKA phosphorylation sites, is expressed in adipocytes of perilipin knockout (Peri KO) mice. Here, we show that despite a normal mitochondrial respiratory capacity, NE-induced lipolysis is abrogated in the interscapular brown adipose tissue (IBAT) of these mice. This lipolytic constraint is accompanied by a dramatic blunting ( approximately 70%) of the in vivo thermal response to NE. Thus, in the presence of perilipin, PKA-mediated perilipin phosphorylation is essential for NE-dependent lipolysis and full adaptive thermogenesis in BAT. In IBAT of Peri KO mice, increased basal lipolysis attributable to the absence of perilipin is sufficient to support a rapid NE-stimulated temperature increase ( approximately 3.0 degrees C) comparable to that in wild-type mice. This observation suggests that one or more NE-dependent mechanism downstream of perilipin phosphorylation is required to initiate and/or sustain the IBAT thermal response.

On the Ia–S relation of the SCS-CN method

The initial abstraction (Ia) versus maximum potential retention (S) relation in the Soil Conservation Service Curve Number (SCS-CN) methodology was revisited, and a new non-linear relation incorporating storm rainfall (P) and S was proposed and tested on a large set of storm rainfall-runoff events derived from the water database of United States Department of Agriculture-Agriculture Research Service (USDA-ARS). Employing root mean square error (RMSE), the performance of both the existing and proposed models was evaluated using the complete database, and for model calibration and validation, data were split into two groups: based on ordered rainfall (P-based) and runoff (Q-based). A specific formulation of the proposed model Ia=λS(P/(P+S))α with λ=0.3 and α=1.5 was found to generally perform better than the existing Ia=0.2S, and therefore was recommended for field applications. When evaluated using the observed Ia data, the proposed version performed significantly better than the existing one.

Fire Rehabilitation Using Native and Introduced Species: A Landscape Trial

Following the 1999 Railroad Fire in Tintic Valley, Utah, we initiated a large-scale fire rehabilitation study comparing a predominately introduced species seed mix used by the US Department of Interior‐Bureau of Land Management (BLM), a mix of native and introduced species provided by the US Department of Agriculture‐Agricultural Research Service (ARS), and 2 nativeseedmixes(highandlowdiversity).Mixeswereseededwitharangelanddrillonthebigsagebrush(Artemisiatridentatavar. wyomingensis [Beetle & A. Young] Welsh) study area whereas the pinyon‐juniper (Pinus edulis Engelm.‐Juniperus osteosperma

Fire Rehabilitation Using Native and Introduced Species: A Landscape Trial

Following the 1999 Railroad Fire in Tintic Valley, Utah, we initiated a large-scale fire rehabilitation study comparing a predominately introduced species seed mix used by the US Department of Interior-Bureau of Land Management (BLM), a mix of native and introduced species provided by the US Department of Agriculture-Agricultural Research Service (ARS), and 2 native seed mixes (high and low diversity). Mixes were seeded with a rangeland drill on the big sagebrush (Artemisia tridentata var. wyomingensis [Beetle A. Young] Welsh) study area whereas the pinyon-juniper (Pinus edulis Engelm.-Juniperus osteosperma [Torr.] Little) woodland study area was aerially seeded followed by 1-way chaining. On drill-seeded plots and by the third year after seeding the native high-diversity mix (16.4 kg pure live seed [PLS] ha-1) had the highest seeded species cover (11.5%) and density (14 plants m-2). Both the BLM (9.3 kg PLS ha-1) and ARS (9.1 kg PLS ha-1) seed mixes had higher seeded species cover (BLM = 8.5%, ARS = 8.2%) and density (BLM = 8.4 and ARS = 7.2 plants m-2) than plots seeded to the low-diversity native mix (8 kg PLS ha-1, cover = 3.8%, density = 3.6 plants m-2). Indian ricegrass (Achnatherum hymenoides [Roemer and J. A. Schultes] Barkworth ‘Nezpar’) in the native high-diversity mix was especially successful on the sandy soils of the drill site, whereas seeds of other species may have been buried too deep for optimum emergence. Aerially-seeded and chained plots had similar and successful seeded species frequency, cover, and density (third-year average = 10.6% cover, 17.2 plants m-2) among all species mixes. All seeded plots had lower cover of annual species than unseeded plots, indicating that revegetation is necessary to reduce weed invasion following catastrophic wildfire in big sagebrush communities lacking residual perennial understory vegetation.

Measured Sediment Yield Rates From Semiarid Rangeland Watersheds

Data describing long-term sediment yield rates on semiarid rangeland watersheds are relatively rare. To augment existing data and gain a better understanding of the controlling variables, sediment yields from 8 subwatersheds within the US Department of Agriculture-Agricultural Research Service Walnut Gulch Experimental Watershed in southeastern Arizona were computed from stock pond sediment accumulation measurements, water level records, and estimates of sediment transported in pond overflows. Sediment accumulation records ranging from 30 to 47 years were evaluated for subwatersheds ranging in size from 35.2 to 159.5 ha. Sediment yield ranged from 0.5 to 3.0 m3 ha-1 y-1, with a mean of 1.4 m3 ha-1 y-1 and a standard deviation of 1.0 m3 ha-1 y-1. As expected, runoff volume was a significant factor (P = 0.005) in explaining the variability in sediment yield, but regression analysis demonstrated other variables are important. For example, the ratio of watershed area to main channel length significantly described (P = 0.06) sediment yield, suggesting that more detailed measurements are needed to characterize channel networks to relate internal watershed sediment transport and deposition processes to sediment delivery at the outlets. To generalize sediment yield rates across rangeland regions, additional research is necessary to determine the relative influence of rainfall and runoff patterns, and watershed physiographic and geomorphic characteristics on sediment transport.

Rapid PCR detection of enterohemorrhagic Escherichia coli (EHEC) in bovine food products and feces

Although Escherichia coli (E. coli) O157:H7 is a major cause of foodborne illness, other types of E. coli can also cause illness. E. coli that possess the eae gene for attachment and effacing have the potential to cause disease. Many real-time, molecular-based assays have been developed to detect Enterohemorrhagic E. coli (EHEC) including E. coli O157:H7. However, no assay currently exists to detect the eae gene present in E. coli O157:H7 and other EHEC strains with a confirmed positive or negative result in less than 12 h. Raw beef food products (raw ground beef and raw boneless beef) at 25 and 375 g samples and bovine fecal samples at 2 g were inoculated with 10(1), 10(3), 10(4), and 10(5) organisms of E. coli O157:H7 to test the sensitivity of this assay. Fourteen different foodborne bacteria (including E. coli O157:H7) and 19 various E. coli strains, obtained from the United States Department of Agriculture-Agricultural Research Service (USDA-ARS) were tested for specificity. E. coli O157:H7 was detected at the level of 10(1) organisms in both 25 and 375 g samples of raw ground and raw boneless beef products as well as 2 g samples of bovine feces after pre-enrichment and concentration. None of the 14 foodborne bacteria screened for cross-reactivity was detected. All USDA E. coli strains confirmed to contain the eae gene were detected.

NEW FLIGHT DISTANCE RECORDED FOR COPTOTERMES FORMOSANUS (ISOPTERA: RHINOTERMITIDAE)

The Formosan subterranean termite (FST), Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), was first introduced to New Orleans after World War II inside infested cargo returning from the Orient (La Fage 1987). For the past 60 years, they have spread throughout the New Orleans metro area, displaced native subterranean termite species, and significantly damaged buildings, trees, boats, and railroad ties in the process. To help combat the problem, the U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) provided funding for treating buildings in a 50-block area of the French Quarter in New Orleans to determine if an area-wide subterranean termite control program is capable of reducing overall populations. Since 1998, populations have been reduced based on structural inspections, termite activity inside independent monitoring stations installed throughout the French Quarter, and the overall number of alates (winged reproductives) recovered from insect glue boards attached to streetlights throughout the French Quarter (Lax & Osbrink 2003). However, alates are still being captured in significant numbers inside selective areas of the French Quarter and along the borders of this treatment zone. Each year during May and June, untold numbers of male and female alates disperse throughout the area in the early evening and tend to congregate around light sources when present. Information on how far they are capable of flying from a dispersal point was virtually unknown, especially in a large urban area. During field observations in early 2004, it appeared that FST alates were flying across the Mississippi River with the aid of prevailing winds and into the French Quarter. To establish if alates were dispersing into the treatment zone from bordering areas, alates were marked with fluorescent visible powders (Shannon Luminous Materials, Inc., Santa Ana, CA) during two dispersal flights on different evenings at a selected site of known termite activity across the Mississippi River, located directly to the southeast of the French Quarter. In cooperation with USDA-ARS, 445 rectangular (20.7 cm × 10.2 cm) glue boards (TRAPPER® LTD, Bell Laboratories, Inc., Madison, WI) were attached to streetlights along the Riverwalk and throughout the French Quarter to capture potentially marked alates. The glue boards were positioned on the streetlights just below the lantern. Weather conditions, including wind velocity and direction, were recorded each evening with a hand-held weather station (Kestrel® 4000, Nielsen-Kellerman, Boothwyn, PA). Alates were individually marked with a bright orange fluorescent powder with a handheld commercial duster as they were flying in a north to northwest direction over the river. These alates were already in flight at the time of marking and their source could not be located. After marking, every glue board was removed and inspected with a UV black light. New glue boards were used for each dispersal flight event. On 1 June 2004, approximately 50 FST alates were initially marked and a single alate was recovered across the River on a glue board 771 m away (Fig. 1). Then, on 7 June, approximately 50 alates were marked again and two alates were recovered on glue boards 866 m and 892 m away (Fig. 1). The wind direction on 1 and 7 June was from the south and southeast at an average speed of 0.93 m/sec and 0.83 m/sec, respectively. Previously, a wind speed at or below 1.0 m/sec was shown to be one of the most important microenvironmental factors involved in determining dispersal flight activity (Leong et al. 1983).

Harvest Mechanization Progress and Prospects for Fresh Market Quality Deciduous Tree Fruits

Deciduous tree fruit crops such as apple (Malus domestica), peach (Prunus persica), and sweet cherry (Prunus avium) are not mechanically harvested for the fresh market. Attempts to mechanically harvest these fruits by mass removal techniques have not been successful due to excessive fruit damage caused during detachment, fall through the canopy, and collection. Robotic harvesters have not been commercially accepted due to insufficient fruit recovery. A U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) harvesting concept shows promise for harvesting both fresh market quality apples and sweet cherries. Successful mechanical harvesting of fresh market quality deciduous tree fruit will only occur when plant characteristics and machine designs are integrated into a compatible system. Cultivar characteristics that would facilitate machine harvesting are uniform fruit maturity at harvest, firm fruit that are resistant to mechanical damage, and compact growth habit that produces fruit in narrow canopies and on short/stiff limbs. Engineers must develop new detachment principles that minimize the energy input to effect fruit detachment, and develop durable energy-absorbing catching surfaces/conveyors to eliminate damage during collection of the fruit. As technology advances, sorting and sizing systems might be developed that can be operating on the harvester to eliminate culls in the field and deliver only fresh market quality fruit to the packers.

USDA-ARS Global Change Research on Rangelands and Pasturelands

T he topic of global change is found almost daily in newspaper and magazine articles and on television. Global change refers to large-scale changes in the Earth's biological, geological, hydrological, and atmospheric systems, whether of human or natural origin. The primary concern of global change has centered on the rapid increase in atmospheric concentrations of primary gases (carbon dioxide [CO2], methane [CH4], and nitrous oxide [N20]) since the Industrial Revolution in the latter part of the 19th century.1 Increased concentrations of all 3 of these gases trap more of the sun's energy close to Earth's surface and lead to global warming, hence the reason that these gases are often referred to as greenhouse The concentration of CO2 has increased by about 35% compared to preindustrial times and is predicted to reach twice the preindustrial concentration within the 21st century.2 Plants convert CO2 in the air into plant tissue, so CO2 enrichment generally stimulates plant growth and improves the efficiency with which plants use water.3 These changes, in turn, influence plant nutrition and the cycling of and other mineral elements through the soil/plant system4 and may have long-lasting ecological consequences for rangelands and pasturelands. For example, increased plant production with CO2 enrichment5'6 requires additional soil nitrogen, which is limiting in most rangeland and pastureland ecosystems, and this will modify nutrient cycling because less nitrogen is available for soil microorganisms to decompose plant materials. The increase in methane and nitrous oxide concentrations in the atmosphere that have occurred are also a cause for concern as their warming potential as gases surpasses that of CO 2.' Global warming is predicted to have numerous impacts on our climate, including altered precipitation patterns and a potential rise in sea levels. As such, global warming may have profound impacts on human activities and enterprises and is thus a concern to many. Rangelands and pasturelands provide much of the world's food and fiber, and because they occupy an extensive land area, changes in how these lands function could increase or reduce the atmospheric load of gases. For example, land management strategies that increase the storage of in plant biomass and/or soil organic matter on rangelands and pasturelands, in a process termed carbon sequestration, offer opportunities to mitigate the rise in atmospheric CO2 concentrations.8 To evaluate potential impacts that increasing concentrations of gases may have, the United States Department of Agriculture-Agricultural Research Service (USDA-ARS), in its Natural Resources and Sustainable Agricultural Systems program, established a Global Change

`Tillamook' and `Pinnacle' Strawberries

‘Tillamook’ and ‘Pinnacle’ (Fig.1) are new June-bearing (short-day) strawberry (Fragaria ×ananassa Duch.) cultivars from the U.S. Department of AgricultureAgricultural Research Service (USDA–ARS) breeding program in Corvallis, Ore., released in cooperation with the Oregon Agricultural Experiment Station, the Washington State University Agricultural Research Center and the Idaho Agricultural Experiment Station. ‘Tillamook’ is a high-yielding, large-fruited, midseason cultivar with very high fruit quality that is suited to the fresh and processed markets. ‘Tillamook’ is named after the Native American tribe who lived along the Pacifi c Coast on Tillamook Bay and current site of the city of Tillamook, Ore. ‘Pinnacle’ is a high-yielding, large-fruited, early midseason cultivar with very high fruit quality that is most suited to the fresh market but produces a satisfactory processed product.

Tolerance to Rust (Puccinia allii) in Seed Derived Garlic Progenies

In California, rust (Puccinia allii) on garlic (Allium sativum) was not considered an economic problem until 1998, when a severe infection of the disease caused an average 51% reduction in yield throughout the state. The weight of harvested bulbs was 25% to 60% smaller than the average weight in the previous year, and soluble solids were reduced by an average of 15%. Until recently, garlic varieties that are resistant or highly tolerant to rust have not been grown in garlic production fields in California. Open pollinated progenies derived from 3 Plant Introduction accessions of the U.S. Dept. of Agriculture-Agricultural Research Service germplasm collection (PI 493099, PI 540315 and W6 12820) were inoculated with a suspension of urediniospores (1, 2 × 105/mL) isolated from rust infected garlic leaves obtained from production fields in Kings, Fresno and Yolo counties. Inoculations were carried out in a replicated experiment in the field under plastic covers, where 12 hours of misting was applied. The disease symptoms were scored on all leaves of the inoculated plants. The size of observed lesions varied from <1 to 280 mm2. Of the 118 plants evaluated, 9.3% had an average leaf area with rust symptoms of less than 1%. The majority of the plants (83.1%) had 1 to 5% of leaf area infected, and over 6% of plants had symptoms on 5 to 25% of their leaf surface. The highest number of plants with a low percent of rust symptoms on leaves was observed on progenies produced from PI 493099. While all maternal plants used to produce the seeds showed rust symptoms, the presence of progenies with ≤0.5% of leaf area infected indicated that a tolerance source to P. allii may exist in the A. sativum NPGS, germplasm collection.

Identification of Lentil Germ Plasm Resistant to Colletotrichum truncatum and Characterization of Two Pathogen Races

ABSTRACT A total of 1,771 lentil accessions from the U.S. lentil collection (U.S. Department of Agriculture-Agricultural Research Service, Pullman, WA) and the Institut für Pflanzengenetik und Kulturpflanzenforschung (Gatersleben, Germany) were screened for resistance to Colletotrichum truncatum, the cause of anthracnose. About 95% of the accessions were susceptible when inoculated with a single isolate in the field. Retesting, under controlled conditions, of accessions rated as resistant or moderately resistant in the field resulted in identification of anthracnose resistance in four accessions from the U.S. collection (PI 320937, PI 320952 [cv. Indianhead], PI 345629, and 468901), and 12 accessions from the German collection (Lens 3, 102, 104, 106, 107, 119, 122, 134, 135, 177, 195, and 209). Seven of the accessions were used as host differentials to characterize pathogenic variability of 50 single-spore isolates collected in Manitoba and Saskatchewan, Canada. The presence of two distinct races was demonstrated. Isolates of C. truncatum avirulent on cv. Indianhead, PI 320937, PI 345629, PI 468901, Lens 102, Lens 104, and Lens 195 were designated race Ct1. Isolates that were virulent on these seven entries were designated race Ct0, indicating their lack of avirulence genes. Race Ct0 was isolated more frequently from commercial seed samples than race Ct1, but the two races were isolated with similar frequency from plants in commercial fields planted to susceptible cultivars. Race Ct0, to which no resistance has yet been identified, presents a high risk to lentil production in Canada and potentially worldwide.

Sources of Partial Resistance to Fusarium Root Rot in the Pisum Core Collection

Fusarium root rot, caused by Fusarium solani f. sp. pisi, is one of the most important fungal diseases of pea and is found in most pea-growing areas around the world. Currently, no commercial cultivars are resistant to this pathogen. Availability of new sources of partial resistance could provide another tool for managing Fusarium root rot. In all, 387 accessions from the Pisum core collection were evaluated for resistance to Fusarium root rot in two independent experiments. Nonparametric analysis of variance conducted on ranks of disease severity for each accession indicated that the two experiments corresponded well. Forty-four plant introduction lines with a disease severity rating of 2.5 or less on a 0-to-5 scale (where 5 = completely rotted) were selected as being partially resistant to root rot. Immunity to Fusarium root rot was not found. Comparison of disease resistance data for Aphanomyces root rot and Fusarium root rot showed a weak, but significant and positive correlation. A complete listing of the data for the partial resistance of all accessions tested can be found at the National Plant Germplasm System website, United States Department of Agriculture-Agricultural Research Service.