THE EFFECT OF EUROPEAN RED MITE, PANONYCHUS ULMI (ACARINA: TETRANYCHIDAE), INFESTATIONS ON N, P, AND K CONCENTRATIONS IN APPLE FOLIAGE THROUGHOUT THE SEASON

1973 ◽  
Vol 105 (2) ◽  
pp. 263-269 ◽  
Author(s):  
H. J. Herbert ◽  
K. P. Butler

AbstractSeasonal trends of the percentage of nitrogen, phosphorus, and potassium were measured in the foliage of apple trees infested with the European red mite, Panonychus ulmi (Koch), at four population levels created by the action of predators and/or chemical treatment.It was shown that by early September the concentrations of these nutrients; particularly nitrogen, were significantly depressed by high P. ulmi populations.

1980 ◽  
Vol 112 (5) ◽  
pp. 527-528 ◽  
Author(s):  
J. P. McCaffrey ◽  
R. L. Horsburgh

The predaceous mirid Deraeocoris nebulosus (Uhler) is found on more than 50 species of ornamental trees and shrubs where it feeds on several important pest species (Wheeler et al. 1975). It is a common mite and aphid predator in commercial apple orchards in Virginia (Parrella et al. 1978). Wheeler et al. (1975) described the nymphal stages and biology, but made no mention of the egg or oviposition site. We describe the egg and oviposition site which we discovered while studying various predators of the European red mite, Panonychus ulmi (Koch), in Virginia apple orchards. Eggs and oviposition sites of other predaceous mirids associated with apple have been described (Kullenberg 1942; Collyer 1952, 1953; Sanford 1964; Horsburgh and Asquith 1968, 1970).


HortScience ◽  
2003 ◽  
Vol 38 (2) ◽  
pp. 234-238 ◽  
Author(s):  
Renae E. Moran ◽  
Dennis E. Deyton ◽  
Carl E. Sams ◽  
Charles D. Pless ◽  
John C. Cummins

Soybean [Glycine max (L.) Merrill] oil was applied to apple trees [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] as a summer spray in six studies to determine if it controls European red mites [Panonychus ulmi (Koch.)], how it affects net CO2 assimilation (A), and if it causes phytotoxicity. Sprays of 0.5%, 1.0%, and 1.5% soybean oil {TNsoy1 formulation [soybean oil premixed with Latron B-1956 (LAT) spreader-sticker at 10 oil: 1 LAT (v/v)]} reduced mite populations by 94%. Sprays of 1% and 2% soybean oil reduced mite populations to three and four mites per leaf, respectively, compared to 25 per leaf on water-sprayed plants. Soybean oil concentrations of 1.0% and 1.5% applied to whole trees reduced A for less than 7 days. Phytotoxicity did not occur when soybean oil was applied with an airblast sprayer at concentrations of 1.0% and 1.5% or with a mist bottle at 2%. Phytotoxicity occurred when soybean oil was applied with a mist bottle at 4% and 6%, which left soybean oil leaf residues of 0.22 to 0.50 mg·cm-2. No phytotoxicity occurred with 4% SunSpray, which resulted in a mean leaf residue of only 0.13 mg·cm-2. Spraying 1% soybean oil tended to give better mite control than 1% SunSpray Ultra-Fine oil, but caused greater oil residues and a greater reduction in A.


1996 ◽  
Vol 121 (5) ◽  
pp. 959-966 ◽  
Author(s):  
A.H.D. Francesconi ◽  
A.N. Lakso ◽  
J.P. Nyrop ◽  
J. Barnard ◽  
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.


1967 ◽  
Vol 99 (7) ◽  
pp. 738-741 ◽  
Author(s):  
R. S. Downing ◽  
T. K. Moilliet

AbstractIn two well-kept but nonsprayed orchards, the European red mite, Panonychus ulmi (Koch), was more numerous and caused more leaf damage to Delicious than to Spartan or McIntosh apple trees. The predacious phytoseiid mites, Metaseiulus occidentalis (Nesbitt) and Neoseiulus caudiglans (Schuster), were more numerous on both Spartan and McIntosh than on Delicious. The differences in the external structure of the leaves may be the reason for the greater abundance of phytoseiids on Spartan and McIntosh.


1960 ◽  
Vol 38 (3) ◽  
pp. 645-653 ◽  
Author(s):  
D. P. Pielou

Examination of a large number of 100-leaf samples shows that the European red mite is distributed contagiously, not randomly, on leaves of apple trees. When the mean number of mites per leaf is plotted against the proportion of mite-free leaves for the corresponding sample, the points fall in a narrow zone, steepest and narrowest at the lower densities. Following application of miticides to heavily infested trees, it is usual to summarize the findings of the tests by grading the performance of the chemicals as excellent, good, etc. according to mite density as determined by s total count from the 100-leaf sample. A method is outlined, in which, by making use of plotted values, a count of mite-free leaves only is sufficient to allow the assessment of performance in such categories.


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