Search Results

You are looking at 1 - 10 of 24 items for :

  • " Panonychus ulmi " x
  • Refine by Access: All x
Clear All
Open access

Hilary F. Goonewardene, E. B. Williams, W. F. Kwolek, and L. D. McCabe

Abstract

Selections of apple (Malus domestica Borkh.) from the cooperative breeding program for disease resistance were evaluated in 3 tests for resistance to the European red mite. Field-collected detached leaves used to determine infestations of motile mites throughout the growing season, dormant twigs used to determine overwintering eggs, and in situ examination of artificially infested leaves of greenhouse-growing whip grafts indicated good sources of resistance. Selections with less hairy leaves supported fewer mites than selections with an abundance of hairs. Selection PRI 1677-2, 1957-1, 2023-1, 2175-7 and 2175-25 show consistently good resistance to the European red mite warranting their use in vegetative propagation or use as parents in breeding for resistance.

Free access

A.H.D. Francesconi, A.N. Lakso, J.P. Nyrop, J. Barnard, and S.S. Denning

The hypothesis that carbon balance is the basis for differences in responses by lightly and normally cropped apple trees to European red mite (ERM) [Panonychus ulmi (Koch)] damage was tested. Mature `Starkrimson Delicious' (Malus domestica Borkh.)/M.26 apple trees were hand-thinned to light (125 fruit/tree, about 20 t/ha) or normal (300 fruit/tree, about 40 t/ha) target crop levels and infested with low [<100 cumulative mite-days (CMD)], medium (400 to 1000 CMD) or high (>1000 CMD) target levels of ERM. A range of crop loads and CMD was obtained. Mite population density, fruit growth, leaf and whole-canopy net CO2 exchange rates (NCER) were measured throughout the growing season of 1994. Leaf area and vegetative growth per tree were also measured. Yield and final mean fruit size were determined at harvest. Return bloom and fruiting were determined the following year. Total shoot length per tree was not affected by crop load or mite damage. ERM reduced leaf and whole-canopy NCER. Normally cropped trees showed fruit weight reduction earlier and more severely than lightly cropped trees with high mite injury. Variation in final fruit weight, return bloom and return fruiting was much better related to whole-canopy NCER per fruit than to CMD.

Free access

A.N. Lakso, G.B. Mattii, J.P. Nyrop, and S.S. Denning

The hypothesis was tested that effects of late-season European Red Mite (ERM) [Panonychus ulmi (Koch)] injury on apple (Malus domestica Borkh.) fruit development are better explained by carbon physiology than by pest densities. Midseason ERM populations were allowed to develop in mature semi-dwarf `Starkrimson Delicious'/M26 trees with moderately heavy crops, then were controlled with miticides at different mite-day (activity of one mite per leaf for 1 day) levels as estimated by weekly leaf sampling. The range of final mite-days was from 250 to 2100 on individual trees. Seasonal fruit growth patterns were monitored. Diurnal whole-canopy net CO2 exchange rate (NCER) was measured in eight clear flexible balloon whole-canopy chambers on several dates before and after mite infestations. Mite injury reduced fruit growth rates. Leaf and whole-canopy NCER were reduced similarly. Late season fruit growth and final fruit size were correlated with accumulated mite-days, but were better correlated to whole-canopy NCER per fruit. Fruit firmness, color, soluble solids and starch ratings showed no correlation to mite-days. Number of flower clusters per tree and final fruit per tree the following year were not related to accumulated mite-days, but final fruit per tree the following year were better correlated to whole-canopy NCER per fruit. These results generally supported the hypothesis.

Free access

A.H.D. Francesconi, C.B. Watkins, A.N. Lakso, J.P. Nyrop, J. Barnard, and S.S. Denning

Fruit maturity, quality, calcium concentration and economic value of `Starkrimson Delicious' (Malus domestica Borkh.) apples, under a range of crop levels and European red mite [Panonychus ulmi (Koch)] cumulative mite-days (CMD), were best explained by local surface regression models involving CMD and crop load. Fruit from trees with low CMD and a light crop (125 fruit/tree, about 20 t/ha) were the most mature at harvest. Those fruit had higher ethylene concentrations, starch pattern indices, soluble solids concentrations, and watercore incidence at harvest than fruit from trees with low CMD and a normal crop (300 fruit/tree, about 40 t/ha), or with high CMD at any crop level. Those fruit also had higher incidences of watercore and internal breakdown after 4 months of cold storage. Calcium concentrations in fruit increased as crop load and CMD increased. Whole-canopy net CO2 exchange rate per fruit related better to fruit quality and calcium concentrations than either crop load or CMD alone, but was always a much worse predictor than local surface regressions. Low CMD and normally cropped trees had the highest crop value; lightly cropped trees had an intermediate crop value; while high CMD and normally cropped trees had the lowest crop economic value. Crop load should be considered when defining action thresholds for mites, and harvest schedules for apples should reflect crop load and mite populations on apple trees.

Open access

William A. McClernan and Richard P. Marini

Abstract

Three European red mite (Panonychus ulmi Koch) population densities (0, 50, and >100 mites/leaf) were maintained on 7-year-old ‘Cresthaven’ peach [Prunus persica (L.) Batsch] trees for 2 seasons. The trees produced a crop only during the first season, but accumulations of 3600 mite-days prior to harvest did not significantly influence yield and fruit quality. Seasonal accumulations of 8900 mite-days did not influence tree growth.

Open access

P. D. Lidster, K. H. Sanford, and K. B. McRae

Abstract

The mortality of European red mite [Panonychus ulmi (Koch)] eggs on fruit of ‘McIntosh’ apple (Malus domestica Borkh.) in storage increased with continuing exposure to low O2 (1.5% CO2 + 1.0% O2) or conventional controlled atmospheres (5.0% CO2 + 3.0% O2) and with elevated storage temperatures to 7.5°C. Lethality was sufficient to provide commercial control for overwintering populations. Susceptibility of red mite eggs differed among years and orchards within years.

Open access

R. W. Zwick, G. J. Fields, and W. M. Mellenthin

Abstract

Population levels of spider mites, principally European red mite, Panonychus ulmi (Koch), were regulated on ‘Newtown’ and ‘Golden Delicious’ apple trees for 4 years. Seasonal fruit sizing and firmness, terminal shoot growth, leaf chlorophyll content, and folio wing-year fruit set were evaluated against mite feeding intensity. Only leaf chlorophyll content of both cultivars and fruit firmness of ‘Golden Delicious’ were unfavorably influenced by mite feeding. Vigorous-growing, nonstressed apple trees possess a relatively high tolerance to seasonal average mite densities of ca. 30 mites/leaf without adverse effects.

Free access

Mark A. Hubbard, James A. Flore, John C. Wise, and James W. Johnson

European red mite (Panonychus ulmi) populations were monitored in a tart cherry (Prunus cerasus `Montmorency') orchard and the effects on photosynthesis determined. Mites levels were controlled in some trees by miticide applications to establish different cumulative mite*days in the trees. Photosynthetic inhibition caused by insect injury was also simulated by spraying other trees with 78 ppm Terbacil at one of four different times during the season, The mite*days accumulated in 1993 ranged from 937 to 2205, however, there were no differences in single leaf or whole tree CO2 assimilation, chlorophyll a fluorescence, or chlorophyll levels among the different levels of mite damage. Likewise, there were no differences in these same parameters among the Terbacil-treated trees except that photosynthesis was reduced on treated trees for 10-14 days, after which photosynthesis recovered to the level of the controls. There were no differences in yield or fruit quality among any treatments, and cold hardiness and return fruiting characteristics will be measured.

Free access

Kendrick N. Mobley and Richard P. Marini

Greenhouse-grown `Imperial Delicious' apple (Malus domestics Borkh.) and `Redhaven' peach (Prunus persica Batsch.) trees were inoculated during the summer with three densities of European red mite (ERM) (Panonychus ulmi Koch) and twospotted spider mite (TSM) (Tetranychus urticae Koch). As ERM- and TSM-days increased, net photosynthesis (Pn), transpiration (Tr), and total chlorophyll content (TCHL) of apple leaves decreased linearly. At similar densities, TSM was more damaging than ERM to apple leaf gas exchange. Water-use efficiency (WUE) of apple declined similarly with increasing mite-days for both mite species. Specific leaf weight (SLW) of apple increased with TSM-days. Pn, Tr, TCHL, and WUE of peach declined linearly with increasing ERM- and TSM-days, and the rates of decline were similar for both mite species. Mites did not affect peach SLW. These results indicate that greenhouse-grown peach is more tolerant than apple to mite feeding.

Free access

Richard J. Campbell and Richard P. Marini

The interaction of N fertilization and European red mite (ERM) [Panonychus ulmi (Koch)] feeding on the physiology of greenhouse-grown `Imperial Delicious' apple (Malus domestica Borkh.) leaves was evaluated. Visual damage was noticeable with 75 mite days (MD) and was consistently greatest on the low-N leaves. Net photosynthesis (Pn) was decreased by mite feeding in all N treatments. However, with equal MD, the high-N treatment retained higher Pn than the low- or medium-N treatments. Transpiration, dark respiration, leaf N, and total chlorophyll increased with N and were reduced by mite feeding. Mite feeding increased dark transpiration at all N levels. Relative water content was unaffected by N and was reduced by mite feeding. Specific leaf weight increased with N and MD.