The most serious disease problem in fraser fir (Abies fraseri) Christmas tree production is phytophthora root rot (PRR). The efficacies of six fungicide treatments in preventing PRR incited by Phytophthora cactorum and P. drechsleri in 2-year-old fraser fir seedlings were evaluated in 2010 and 2011 in central Pennsylvania. The study examined five fungicide drench treatments [dimethomorph, fosetyl-aluminum (fosetyl-Al), hydrogen dioxide, mefenoxam, propamocarb hydrochloride] and one soil spray treatment (mefenoxam) in raised planting boxes. Dimethomorph applied on 14-day intervals prevented foliar disease symptoms and mortality in fraser fir seedlings exposed to either P. cactorum or P. drechsleri. One-time application of fosetyl-Al or mefenoxam were effective at times in preventing foliar disease symptoms and mortality in fraser fir seedlings exposed to P. drechsleri but were not as effective against P. cactorum.
Benjamin K. Hoover and R.M. Bates
Benjamin K. Hoover and R.M. Bates
The susceptibility of fraser fir (Abies fraseri), canaan fir (A. balsamea var. phanerolepis), and nordmann fir (A. nordmanniana) to phytophthora root rot (PRR) incited by Phytophthora cactorum or P. drechsleri was assessed in two experiments in central Pennsylvania. In an 8-week greenhouse study, seedlings and transplants growing in soilless substrate were inoculated with Phytophthora in flooded and non-flooded settings. In an 8-week outdoor study conducted in raised planting boxes filled with soil, transplants were inoculated with Phytophthora species in well-drained and poorly drained soil. Based on foliar disease ratings, mortality rates, and dry shoot and root weights, differences in susceptibility to P. cactorum and P. drechsleri existed between these true fir (Abies) species. Fraser fir was very susceptible to P. cactorum and P. drechsleri. Canaan fir had strong resistance to P. cactorum and P. drechsleri in well-drained settings but was susceptible in poorly drained settings. Nordmann fir had very strong resistance to P. cactorum and P. drechsleri in both well-drained and poorly drained settings.
J.R. Schupp, M.M. Bates. and H.J. Brummer
`Empire' is a popular new apple with fruit growers in the northeastern United States, noted for producing small-sized fruit. To test the efficacy of chemical thinners and rootstocks for increasing fruit size of `Empire', three-tree plots containing trees on M.7 EMLA, MM. 111, and seedling rootstocks were chemically thinned at petal fall with 10 ppm NAA or 85 ppm 6 BA, applied as Accel. Both NAA and Accel reduced fruit set. Trees on M.7 EMLA had higher set than trees on seedling. Yield was highest on M.7 EMLA and lowest on seedling. Fruit diameter after final set in July was increased by both chemical thinners and was greater for both clonal rootstocks than for seedling. Fruit on seedling trees were delayed in maturity relative to the two clonal rootstocks. Accel increased the number of fruit 70 mm or greater in diameter, while NAA increased the number of fruit in the 64- to 69-mm-diameter class. Analysis of covariance with crop load suggested that the increase in fruit size associated with Accel was a direct effect rather than a secondary effect from thinning.
J.R. Schupp, H.A. Schupp and M.H. Bates
A study was conducted in 1992 at Highmoor Farm, Monmouth, ME to test the effects of fish hydrolysate fertilizer on fruit set, fruit size and fruit quality of apple. Mature, semi-dwarf `Delicious' and `Golden Delicious' trees received 2.76g/1 N, supplied by either fish hydrolysate fertilizer or urea, or received no fertilizer (control). Fertilizers were applied via three foliar sprays applied at seven day intervals, beginning at petal fall. Fish hydralysate fertilizer reduced fruit set of `Delicious' and `Golden Delicious'. Foliar urea increased fruit set and yield of 'Golden Delicious'. Neither fertilizer affected mineral nutrient concentrations of leaves collected in July. Fish hydrolysate increased fruit russeting on both cultivars. Fish hydrolysate is not recommended as a foliar fertilizer for apples.
Terence R. Bates, Richard M. Dunst and Paula Joy
Three-year-old field-grown 'Concord' (Vitis labruscana Bailey) grapevines were destructively harvested at eight growth stages during 1998 to quantify growth, carbohydrate distribution, and nutrient concentrations of different organs. The roots were the major storage organ for carbohydrates and nutrients, accounting for 84% of the starch and 75% of nitrogen stored in the vines at the beginning of the season. About 78% of the reserve starch in the vine was used for prebloom root and shoot growth. Early-season fine-root growth was a sink for stored vine nitrogen; however, the fine roots quickly became a nitrogen uptake source, providing at least 84% of the spring growth nitrogen. Total root biomass increased from bloom to leaf fall, but reserve carbohydrates and nutrients lost in the prebloom period did not begin to recover in roots until the end of rapid shoot development in late July. Crop removal at harvest, and a late-season root flush, further increased vegetative carbohydrate and nutrient reserves in the short postharvest period.
Terence R. Bates, Richard M. Dunst, Theodore Taft and Michael Vercant
One- and 2-year-old 'Concord' (Vitis labruscana L.) grapevines were used to study the effect of soil pH on vegetative growth and nutrition. Ninety-eight, own-rooted, 'Concord' grapevines were planted in 94.6-L pots containing vineyard soil adjusted to seven soil pH levels ranging from 3.5 to 7.5. After the first growing season, seven vines from each soil pH treatment were randomly selected, destructively harvested, and measured for root and shoot growth. The remaining 49 vines over-wintered in the pots, were defruited in year two, and were destructively harvested at the end of the second growing season. There was a reduction in root biomass below soil pH of 4.5 and a greater reduction in shoot biomass leading to a higher root: shoot ratio. There were no significant differences in vegetative growth of young 'Concord' vines from a soil pH of 5.0-7.5. However, there was a trend toward lower shoot biomass and higher root: shoot ratio at the highest soil pH level. Phylloxera nodosities on roots were present in equal densities at all soil pH values. However, the negative impact of phylloxera on vine dry mass was greater on vines under nutrient stress at the highest and lowest pH treatments than on those with adequate nutrition at the mid-range soil pH values.
Kathleen M. Kelley, Janine R. Stumpf, James C. Sellmer and Ricky M. Bates
Consumers were surveyed at the 2004 Philadelphia Flower Show in Philadelphia, Pa. from 8–10 Mar., to quantify their attitudes and behaviors towards invasive plant species and the potential problems associated with purchasing and planting invasives in the landscape. A majority of the 341 participants (81.5%) was aware that non-native exotic plants were used in the landscape and that these plants may be invasive in natural areas. Less than half (40.1%) acknowledged owning plants that were considered invasive, while one-third (33.5%) did not know. Less than half (41.3%) believed that laws should be passed to prevent sale of non-native exotic plants, while 27.8% believed that laws should be passed to allow sale of only native plants in their area. Three distinct consumer segments were identified using cluster analysis: “Invasive savvy,” participants knowledgeable about invasives and interested in alternative species; “Invasive neutral,” participants neutral in their decision to purchasing alternatives to invasive plants and price sensitive in regard to paying more for plants tested for invasiveness; and “Invasive inactive,” participants opposed to purchasing genetically modified plants or those bred to be seedless. Survey results indicated that media sources (e.g., television and newspapers/magazines/books) would be effective for educating consumers about potential problems associated with invasive species in the landscape.
K.M. Batal, D.R. Decoteau, J.T. Garrett, D.M. Granberry, D.C. Sanders, J.M. Davis, G.D. Hoyt and R.J. Dufault
Cucumber and potato crops were tested in a rotation with winter cover crops at different locations in Georgia, North Carolina, and South Carolina from 1991 to 1994. Biomass DM of vegetable crops was greatest when grown after crimson clover. Clover plantings resulted in a greater biomass than wheat when preceded spring cucumber crop. Vegetable biomass produced on clover plots or with N rates of 60 to 120 kg·ha–l was equivalent. Nitrogen recovery by cover and vegetable crops was enhanced by clover plantings. Clover biomass (tops only) provided an average of 138 kg N/ha for the cucumber crop, compared to an average of 64 kg N/ha provided by wheat. Nitrogen recovery by vegetable crops was also enhanced with 60–120 kg N/ha rates. Yields were highest when high N rates were used and when crops were produced on clover plots. Vegetable yield, cover crop biomass, and N recovery were positively correlated with vegetable biomass and applied N.
Dennis R. Decoteau, J.M. Davis, G.D. Hoyt, K.M. Batal, D.C. Sanders, J.T. Garrett and R.J. Dufault
A 5-year study using winter cover crops (wheat or rye, crimson clover, and fallow) in a tomato and bean rotation indicated several soil responses to the cover crops. Advantages of crimson clover winter cover crop to the soil in a tomato-bean rotation included adding organic matter to the soil, which resulted in an increase in the amount of inorganic nitrogen in the upper levels of the soil profile and an increase in the soil's water-holding capacity. An additional benefit of winter cover crops to the soil was the potential of reduced nitrogen leaching.
K.M. Batal, D.R. Decoteau, D.M. Granberry, B.G. Mullinix, D.C. Sanders, G.D. Hoyt and R.J. Dufault
Pepper and sweet corn were tested in a rotation with crimson clover and velvet bean (Mucuna pruriens) cover crops at different locations in Georgia, North Carolina, and South Carolina from 1995 to 1996. Vegetable production with minimum-till following the cover crops was compared with two different conventional methods (following rye cover or fallow). All minimum-till/cover crop treatments caused reduction of total number of pepper fruit, compared to the conventional methods. Effects on premium grade (Fancy + U.S. #1) were similar to the effects on total fruit. The highest percentage of premium grade was produced by both conventional methods in 1996. Sweet corn responded similarly to these treatments in 1995. However, in 1996, clover plots had corn yields nearly as good as the conventional plots. As in bell pepper, plots with velvet bean cover produced lower yield in 1996. Treatment effects on number of marketable corn were the same as the effects on total ears produced.