Distal Leaf Research Articles

The Identity of Grimmia involucrata Cardot (Grimmiaceae, Musci)

Grimmia involucrata is a Mexican en- demic that has been confused with G. affinis, G. americana, and G. tergestina. It is recognized here as a valid, morphologically distinct species char- acterized by clavate stems, a gonioautoicous con- dition, differentiated perichaetial leaves, immersed sporophytes, and the smooth basal third of the outer plate of the peristome teeth. It is illustrated herein. Grimmia involucrata was described by Cardot (1909) on the basis of a specimen collected in the state of Hidalgo, Mexico. Reference to this species was made by Thgriot (1931), who listed specimens collected by Amable in Mexico City; Sayre (1952) and Whitehouse and McAllister (1954) treated it as conspecific with G. americana Bartram, a species described from Texas (Bartram, 1929). Crum and Anderson (1981: 424) disagreed and concluded that G. involucrata was not even a member of the when dry, erect-spreading when moist, oblong- ovate, 0.9-1.3 mm in length; apex obtuse; distal leaf margins bistratose, plane, entire. Distal leaf cells quadrate to short rectangular, in 2(-3) layers of thick-walled, slightly sinuose cells, 5-12 im diam.; marginal leaf cells at base quadrate to short rectangular or transversely elongated, with thicker cross walls, 7-17 im diam.; other basal cells uni- stratose, quadrate to rectangular, thick-walled, slightly sinuose upward; basal juxtacostal cells not forming a distinct area, mostly quadrate and thin- walled. Costa excurrent, in section with one dorsal substereid layer and 2-6 guide cells around or ven- tral to an internal hydroid group. Hair-point 0.6- 1.3 mm long, denticulate, slightly decurrent at base. Gonioautoicous. Perigonial bracts convolute, 0.6 mm long. Perichaetial leaves strongly differ- entiated, the outer with a hyaline marginal area, the inner mostly thin-walled and hyaline; oblong-ovate to convolute, 1.4-1.9 mm long; hair-point 0.9-1.6 mm long. Seta straight, 0.5 mm long, not twisted. Capsule symmetrical, ellipsoid, immersed, 1.2-1.4 mm long; peristome teeth somewhat cribrose, del- toid, 287-300 x 62-75 jm, straw-colored to or- ange, outer plate nearly smooth in the lower third, trabeculate, distally papillose; inner plate finely pa- pillose throughout; annulus revoluble; exothecial cells prismatic, mostly longer than wide, thin- walled, 25-60 im diam.; stomata several, basal; operculum conic, short-rostrate, 0.7 mm long; ca- lyptra mitrate, smooth, 0.9-1 mm long. Spores 10- 15 Ism diam., spore wall perforated.

Seasonal Insecticide Evaluation for Pear Psylla, 1997

Abstract Experimental sprays were applied to single-tree replicated plots in a block of ‘Bartlett’ (84%), ‘Bosc’ (9%), and ‘D’Anjou’ (7%) pears. Trees were planted to a spacing of 24 X 24 ft and were 18 years old. Each treatment was replicated 4 times in a randomized block design. All plots except the dilute treatment of M-96-018 were applied with an Friend Airblast ‘393’ sprayer calibrated to deliver 100 gpa at 2.1 mph. The dilute treatment of M-96-018 was treated with a handgun at 400 psi from a truck-mounted sprayer equipped with a Kohler 23-gpm pump. All plots received a regular fungicide maintenance schedule of Benlate 50 DF, Agrimycin, and Ziram 76 WP. All treatments were evaluated by counting eggs and/or nymphs from leaf samples using a binocular microscope under 10X magnification at 4-17 day intervals. Counts were made on 15 spur leaf samples from 5 May to 27 May, on 8 spur and 7 third most distal leaf samples on 2 Jun, and on 15 third most distal leaf samples from 9 Jun until 10 Jul. The cumulative number of PP nymph days per leaf was determined for each treatment from 5 May to 10 Jul. Adult PP were sampled by making a 2-min observation around the periphery of each tree. Russet evaluations were done on pear fruits (30 per replicate). Each replicate was rated as 0 (no russet), 1 (raised lenticels), 2 (1-10% russeted surface), 3 (11-25% russeted surface), 4 (26-50% russeted surface), or 5 (>51% rus-seted surface). The individual ratings were added to calculate a russet rating for each replicate. Possible ranges for the replicate russet ratings (and esti-mate of range of % of surface russeted) are 0-30 (none to raised lenticels), 31-60 (raised lenticels to 1-10% russeted surface), 61-90 (1-10% to 11-25% russeted surface), 91-120 (11-25% to 26-50% russeted surface), and 121-150 (26-50% to >51% russeted surface). Pest pressure was moderate throughout the season.

Comparison of Detection Methods for Citrus Tristeza Virus in Field Trees During Months of Nonoptimal Titer.

Enzyme-linked immunosorbent assay (ELISA) can reliably detect citrus tristeza virus (CTV) in samples collected during approximately 6 months of a typical year. Two reverse transcriptase polymerase chain reaction (RT-PCR) methods (total nucleic acid extract and immunocapture based) were evaluated and compared to ELISA in order to develop a more sensitive assay for CTV. From May 1994 to October 1995, 6 sweet orange trees infected with CTV from each of 2 geographic areas (Riverside and the San Joaquin Valley) were tested monthly by each method. In the months of August (San Joaquin Valley samples) and September (Riverside and San Joaquin Valley samples) several of the trees had a significant loss of virus titer such that CTV was not reliably detected by ELISA. By contrast, the 2 PCR methods gave definitive positive results for CTV in samples collected during these months. Different tissue types were analyzed by each of the above assays. Petioles and midribs, both phloem-rich tissues, were each satisfactory for ELISA, while distal leaf tips did not always produce a positive result. All tissue types were equally efficient in producing a positive result in both PCR-based assays. The results of this study provide a basis for CTV testing by PCR in months when virus titer drops to a level generally unacceptable for using ELISA.

Pear, Seasonal Insecticide Evaluation for Pear Psylla, 1996

Abstract Ten insecticide treatments, either single compounds or combinations of various insecticides, were evaluated for their ability to control PP on a seasonal basis. The experimental sprays were applied to single-tree replicated plots in a block of ‘Bartlett’ (84%), ‘Bosc’ (9%), and ‘D’Anjou’ (7%) pears. Trees were planted at a spacing of 24 X 24 ft and were 17 years old. Each treatment was replicated 4 times in a randomized block design utilizing the cv. Bartlett. Experimental sprays were applied with a handgun at 400 psi from a truck mounted sprayer equipped with a Kohler 23 gpm pump. All plots received a regular fungicide maintenance schedule of Benlate 50DF, Streptomycin and Ziram 76WP. All treatments were evaluated by counting eggs and/or nymphs from leaf samples using a binocular microscope under 10X magnification at 3-12 day intervals. Counts were made on 15 spur leaf samples from 6 May to 20 May, on 8 spur and 7 third most distal shoot leaf samples 28 May, and on 15 third most distal leaf samples from 6 Jun-27 Jun. Adult PP were sampled by making 2-minute observations around the pe-riphery of each tree. Russet evaluations were made on pear fruits (25 per replicate). Each replicate was rated as 0 (no russet), 1 (raised lenticels), 2 (1-10% russeted surface), 3 (11-25% russeted surface), 4 (26-50% russeted surface), or 5 (>51% russeted surface). The individual ratings were added to calcu-late a russet rating for each replicate. Possible ranges for the replicate russet ratings (and estimate of range of % of surface russeted) are 0-25 (none to raised lenticels) 26-50 (raised lenticels to 1-10% russeted surface), 51-75 (1-10% to 11-25% russeted surface, 76-100 (11-25% to 26-50% russeted surface), and 101-125 (26-50% to >51% russeted surface). Pest pressure was moderate throughout the season.

Determination of nitrogen status in maize senescing leaves

Chlorophyll meters have been successfully used in assessing leaf greenness and nitrogen (N) status for several crops, but for plants with large leaves such as maize (Zea mays L.) within‐leaf blade variations in meter readings may contribute an additional error in determining leaf N status. Within‐leaf variation is highest during the senescence period when chlorophyll meters can be an important selection tool for identifying genotypes with the stay‐green as opposed to early‐senescent trait. Two hundred forty leaves were sampled from an ongoing field experiment involving two contrasting hybrids ('Pride 5’, an early senescing hybrid, and ‘Pioneer 3902’, a stay‐green hybrid) grown at three N fertilizer rates (0, 100, 200 kg N ha‐1) to determine the better measurement position for rapid, non‐destructive field assessment of leaf N status. Each leaf blade was divided into two equal length segments: the proximal segment adjacent to the stalk and the distal (or tip) segment. Paired SPAD‐502 meter readings and leaf samples for laboratory N concentration determination were obtained from each segment. Total leaf N concentration was better estimated by SPAD‐502 meter readings on leaf distal segments at 2 wk (r=0.91, P<0.01) and 5 wk after silking (r=0.65, P<0.01) than by meter readings on proximal leaf segments. Our results indicate that as corn leaves senesced, total leaf N concentration was better estimated by distal leaf segment samples than by proximal segment samples. Furthermore, senescence was evident on distal leaf segment samples before proximal leaf segments and grain yield was positively correlated (r values ranged from 0.80 to 0.92) with distal leaf N levels from 2 wk to 5 wk after silking.

Dikegulac-sodium Spray Enhances Uniform Regrowth of Murraya paniculata (L.) Jack Hedge

An aqueous solution of dikegulac-sodium at 0, 2000, 4000, 6000, or 8000 mg a.i./liter was sprayed on a mature Murraya paniculata hedge as the first leaves expanded on newly developing lateral shoots after trimming. The lateral shoots from each 0.09-m2 hedge surface elongated less and the coefficient of variation (cv) decreased as the growth regulator concentration increased. Application of dikegulac-sodium at 4000 mg a.i./liter to the most distal leaf on topped, single-leader seedlings inhibited the elongation of distal shoots while it enhanced proximal shoot growth. Dikegulac-sodium spray between 4000 and 6000 mg a.i./liter to the hedge decreased apical dominance among lateral shoots and enhanced uniform regrowth without causing visible damages. The cv reduction was attributed to the growth regulator-induced weakening of apical dominance. Chemical name used: sodium salt of 2,3:4,6-bis-O-(1-methylethylidene)-α-l-xylo-2-hexulofuranosonic acid (dikegulac-sodium).

Influence of xylem vascular architecture on the translocation of phosphorus from nodal roots in a genotype of Trifolium repens during undisturbed growth.

Our objective was to establish whether the xylem vascular connections (architecture) of a genotype of Trifolium repens L. had implications for the intraplant allocation of recently assimilated phosphorus (P). One nodal root of each plan! was isolated and fed 32 P-labelled nutrient solution for 24 h. The fed root was either on the parent axis (11-12 nodes proximal CO the apex) or on a branch at the third or fourth node along the branch when counting from the junction with the parent stolon. Allocation patterns were obtained by dissecting plants and assaying each dissected component for 32 P. Under conditions of undisturbed growth in a controlled environment xylem architecture was found to have an important influence on the intraplant distribution of 32 P from nodal roots. Allocation patterns of 32 P were consistent with those predicted from knowledge of the xylem vascular architecture of the genotype and a predominantly acropetal direction of the transpiration stream. For instance, very little 32 P (< 1 % of exported 32 P from the fed root) was found in branches on the opposite side of the stolon to the fed root, and the strong acropetal direction of the transpiration stream resulted in little allocation of 32 P to leaves that had traces that arose from axial bundles at positions proximal to that of the fed root (the leaf subtending the fed root and the next distal leaf had low 32 P content), to all plant organs proximal to the fed root (< 6%) and to all other roots (<4%). The high allocation of 32 P to the branch arising at the same node as the fed root (64%) reflects the numerous links that the- fed root has to vascular bundles in the branch (3-6, of which two are axial bundles) against the single connection it has to the adjacent lower axial bundle in the parent stolon. Allocation of 32 P to the leaf and axillary bud at each node along the branch strongly favoured nodes on the adaxial side, a result consistent with the fact that the root connections are to the upper and lower axial bundles on the adaxial side of the branch. Allocation to a particular node along the branch was also influenced by its nodal position relative to the fed root and the sink strength of its tissues for the transpiration stream.

Apple, Preliminary Insecticide Testing, 1995

Abstract Dilute sprays were applied with a hand sprayer (450 psi) at pink (9 May), petal fall (26 May), and as cover sprays on 14 Jun, 29 Jun, 10 Jul, 26 Jul, 7 Aug, and 20 Aug. Treatments of the standard compound, Guthion, were applied at pink, and petal fall through sixth cover. Comply and CGA-59205 were applied at pink and first cover and Guthion 3F was applied alone in the other sprays (petal fall and second through sixth cover). Several schedules of V71639 were compared; (1) A complete seasonal schedule applied at pink, petal fall, and in the first through sixth cover sprays. (2) A pink and first cover spray. (3) A petal fall and second cover spray. Guthion 3F was applied alone to fill in the other normal spray intervals in the reduced programs (2 &amp; 3) of V71639. Treatments were replicated 3 times on a single tree plot of ‘McIntosh’ apples and arranged in a RCB design. Damage from early-season plum curculio and the first generation of codling moth were estimated by sampling 100 apples on the tree in each replication on 5 Jul. At harvest (6-12 Sep) 100 apples from each replication were evaluated for insect damage. ERM and predaceous mites were sampled on 25 randomly selected leaves/replication on 4 Aug. On 6 Jul (7 days post-treatment) aphids were counted on the second or third distal leaf on each of 10 actively growing terminals in each replication. WALH were counted on 25 spur leaves on 29 Aug. First generation STLM tissue mines were counted on 25 fruit clusters from the ‘McIntosh’ trees in each replication on 21 June. Second generation STLM tissue mines were counted on the six distal leaves on 10 randomly selected “hardened off” terminals/replication on 29 Aug.

Pear, Seasonal Insecticide Evaluation for Pear Psylla, 1995

Abstract Experimental sprays were applied to replicated 3-tree plots in a block of ‘Bartlett’ (84%), ‘Bosc’ (9%), and ‘D’Anjou’ (7%) pears. Trees were planted at a spacing of 24 X 24 ft and were 16 years old. Each treatment was replicated 4 times in a randomized block design. Experimental sprays were applied with a Friend Airmaster ‘309’ calibrated to deliver 100 gpa at 2.2 mph. The first table contains a listing of the application dates. All plots received a regular fungicide maintenance schedule of Benlate 50DF, Streptomycin and Ziram 76WP. All sampling was conducted on the middle ‘Bartlett’ tree in each replicate. All treatments were evaluated by counting eggs and/or nymphs from leaf samples using a binocular microscope under 10 X magnification at 6-9 d intervals. Counts were made on 15 spur leaf samples from 1 May to 25 May, on 8 spur and 7 third most distal leaf samples from 1 Jun to 14 Jun, on 15 third most distal leaf samples on 22 Jun to 7 Jul. Adult PP were sampled by making 2 taps on 8 limbs per center plot tree. All adults dropping onto a 0.2 m2 collecting tray were counted. Russet evaluations were made on pear fruits (30 per replicate). Each replicate was rated as 0 (no russet), 1 (raised lenticels), 2 (1-10% russeted surface), 3 (11-25% russeted surface), 4 (26-50% russeted surface), or 5 (&amp;gt;51% russeted surface). The individual ratings were added to calculate a russet rating for each replicate. Possible ranges for the replicate russet ratings (and estimate of range of percent of surface russeted) are 0-30 (none to raised lenticels), 31-60 (raised lenticels to 1-10% russeted surface), 61-90 (1-10% to 11-25% russeted surface), 91-120 (11-25% to 26-50% russeted surface), and 121-150 (26-50% to &amp;gt;51% russeted surface).

Pear, Seasonal Pear Psylla Control Experiment, 1994

Abstract Experimental sprays were applied to replicated three tree plots in a block of ‘Bartlett’ (84%), ‘Bosc’ (9%), and ‘D’Anjou’ (7%) pears. Trees were planted to a spacing of 24 × 24 ft and were 15 years old. Each treatment was replicated four times in a RCB design. Experimental sprays were applied with a Friend Airmaster ‘309’ calibrated to deliver 100 gpa at 2.2 mph. All plots received a regular fungicide maintenance schedule of Benlate 50DF, Streptomycin and Ziran 76WP. All sampling was conducted on the middle ‘Bartlett’ tree in each replicate. All treatments were evaluated by counting eggs and/or nymphs from leaf samples using a binocular microscope under 10X magnification at 5-14 d intervals. Counts were made on 15 spur-leaf samples from 6 May to 18 May; on 5 spur and 10 third most distal leaf samples from 24 May to 30 Jun; and on 15 third most distal leaf samples on 7 Jul to 28 Jul. Adult PP were sampled by making two taps on eight limbs per center plot tree. All adults dropping onto 0.2 m2 collecting tray were counted. Pear fruits (25 per replicate) were rated as 0 (no russet), 1 (1-10% russeted surface), 2 (11-25% russeted surface), 3 (26-50% russeted surface), or 4 (&amp;gt;51% russeted surface). Possible ranges are 0-30 (none to 1-10% russeted surface), 31-60 (1-10% to 11-25% russeted surface), 61-90 (11-25% to 26-50% russeted surface), and 91-120 (26-50% to &amp;gt;51% russeted surface).

OBTENÇÃO in vitro DE BROTOS DE Begonia rieger COM THIDIAZURON, CINETINA E ÁCIDO NAFTALENO ACÉTICO

Com o objetivo de determinar um protocolo adequado à obtenção de brotos aéreos de Begonia rieger, cultivaram-se segmentos de pecíolos, discos foliares basais e distais, em meio MS completo, testando-se quatro combinações de ácido naftaleno acético (ANA) e cinetina (0,01 + 0,1; 0,05 + 0,5; 0,1 + 1,0; 0,2 + 2,0mg/l) e duas combinações de ANA e thidiazuron (TDZ) (0,01 +0,1; 0,01 +0,25mg/l). Os discos foliares basais mostraram-se mais eficientes na formação de brotos (60-80%) sem raízes, enquanto que os pecíolos foram mais eficientes na formação de brotos com raízes. Para os discos foliares distais o melhor tratamento foi de 0,1 e 1,0mg/l de ANA e cinetina. O uso de TDZ a 0,1 mg/l teve maior eficiência na formação de brotos sem raízes (60%) para todos os explantes estudados. O material tratado com o TDZ apresentou maior número de brotos aéreos do que com a cinetina. Quando associou-se 0,1 + 1,0mg/l de ANA e cinetina, os discos foliares distais formaram maior número (52/explante) de brotos. Na menor concentração de TDZ houve maior número de brotos, 80 e 90 por explante, nos discos foliares distais e basais, respectivamente. Nos pecíolos, a maior concentração de TDZ formou maior número de brotos. Em ambas concentrações de TDZ, as culturas permaneceram em ativo crescimento vegetativo, ao contrário das crescidas em meio com cinetina, cujos brotos oxidaram e morreram.

Lichen succession on Wilkiea macrophylla leaves

Abstract: Changes in foliicolous lichen populations of the shrub Wilkiea macrophylla in rainforest at Mt Glorious (south-east Queensland) were observed in the field for 3 years. Leaves successively distal from the twig apices were treated as a chronosequence for lichen successional studies. Five species of lichen each colonized more than 50% of the leaves, and leaves successively distal from the apex showed increasing mean species number. Lichen cover rose until the seventh most distal leaf from the first colonized leaf along a twig, reaching 52%. More distal (older) leaves had apparently lower cover. Different lichen species show different instantaneous colonization rates that vary with time. The sequence of lichen colonization and subsequent community composition is best described by a 'Tolerance' model of succession if a single leaf is selected as the unit or with a 'Chronic Disturbance' model if a leaf population is considered.

Pear, Insecticide Evaluations, 1992

Abstract Mature ‘Bartlett’ pear trees were sprayed with handguns operating at 600 psi to evaluate pesticides for control of pear pests. Plots consisted of 5 single-tree replicates in randomized block design. All treatments except Agridyne and NTN 33893 at 6.7 oz were applied 23 Apr, 19 May and 20 Jul. Agridyne was applied 23, 30 Apr, 7 May and 1, 8, 15 Jun. NTN 33893 at 6.7 oz was applied 23 Apr and 19 May. Treatments were evaluated for PP control by counts made at 2-wk intervals. Adult PP were counted from a 5-beating-tray sample per replication. PP nymphs were counted from a 25-leafsample per replicate. Samples prior to 26 May consisted of fruiting spur leaves, those during the remainder of the season consisted of the proximal leaf, distal leaf and 3 leaves from the middle of 5 terminal shoots. Leaves were brushed and resulting slides were examined under 10 X magnification. Fruit damage by insects and mites was rated according to US grade standards for fresh market ‘Bartlett’ pears on 2 samples of 25 mature fruits per replication. Factors of fruit quality including firmness, soluble solids and size were evaluated from 2 10-fruit samples per replicate at normal harvest maturity. Fruit and foliage were examined for phytotoxicity after each spray.

Pear, Season Pear Psylla Control Experiment, 1992

Abstract Experimental sprays were applied to replicated 6-15 tree plots in a block of ‘Bartlett’ (84%), ‘Bosc’ (9%), and ‘D’Anjou’ (7%) pears. Trees were planted 24 x 24 ft apart and were 14 years old. Each treatment was replicated 4 times. Treatments were applied dilute to run off with a handgun from a truck mounted hydraulic sprayer at 400 psi. An average of 2.3 gal were applied per tree at 190 gal/acre. Insecticide application dates varied among treatments and are listed in the table. All plots received a regular fungicide maintenance schedule of Benlate 50 DF, Streptomycin, Ziram 76 WP, and Topsin-M 85 DF. All sampling was conducted on the middle ‘Bartlett’ tree in each replicate. All treatments were evaluated by counting eggs and/or nymphs from leaf samples at 6-17 day intervals. Counts were made on 10 spur leaf samples from 11-18 May, on 7 spur and 8 third most distal leaf samples from 26 May to 16 Jun, and on 15 third most distal leaf samples from 22 Jun to 15 Jul.

Distribution, Conditioning, and Interspecific Effects of Blackmargined Aphids and Yellow Pecan Aphids (Homoptera: Aphididae) on Pecan

Field studies on the yellow pecan aphid Cornplex showed that, among leaves growing from the same bud, the distal younger and larger leaves of pecan, Carya illinoensis (Wang.) K. Koch, were able to support a higher number of blackmargined aphids, Monellia caryella (Fitch), and yellow pecan aphids, Monelliopsis pecanis Bissell, than the proximal older and smaller leaves, before the leaves become unsuitable for further aphid development. Cumulative aphid days (one aphid on one leaf for 1 d = 1 aphid d) required to render foliage unsuitable for further development ranged from 421 on the most distal leaf to 50 on the most proximal leaf of the same shoot for blackmargined aphids during a 2-mo period, and from 15,132 to 1,322 for yellow aphids during a 4-mo period in separate infestations. Results of sequential infestations where foliage was initially subjected to an epidemic of black margined aphids averaging 18,900 aphid-d per 10 leaves showed that the foliage would support 20,345 aphid-d of yellow pecan aphid development; the reciprocal sequential infestation experiment following a yellow pecan aphid epidemic of 100,861 aphid-d per 10 leaves resulted in the foliage supporting 74 aphid-d of black margined aphid development. Foliage conditioned by blackmargined aphid remained suitable for subsequent infestation by substantial numbers of yellow pecan aphids, but the latter species caused substantial defoliation, rendering foliage unsuitable in the reverse situation. The average calendar time of infestation was 64 d for the blackmargined aphid and 114 d for the yellow pecan aphid.

Pear, Prebloom Applications of Insegar for Control of Pear Psylla, 1991

Abstract Mature bearing pear trees were sprayed with air carrier equipment applying 400 gal per acre to test prebloom applications of Insegar for control of PP. Plots consisted of unreplicated blocks of 1/2 acre or larger. Treatments were applied at delayed dormant (20 Mar) and at clusterbud (8 Apr) stages of tree development. Additional sprays applied to the entire orchard during the growing season included Dimilin 25% WP 1 lb/acre plus superior type oil 1 gal/acre on May 31, Guthion 35% WP 2.5 lb/acre plus Vendex 4 L 2 pt/acre on 11 Jul and Guthion 35% WP 2 lb/acre plus Mitac 50% WP 3 lb/acre on 31 Jul. Treatments were evaluated by adult, egg, and nymph counts on several dates after treatment. Adults were counted by the limb tap method. Early season eggs and nymphs were counted on fruiting spurs collected at random from test plots and examined under magnification in the laboratory. Later egg and nymph samples were counted from 2 50-leaf samples per plot. Leaf samples consisted of the proximal leaf, distal leaf, and 3 leaves from the middle of 10 terminal shoots. Leaves were brushed and resulting slides were examined under magnification. PP russet was rated according to US grade standards for fresh market 'Bartlett' and 'd'Anjou' pears on 2 samples of 25 mature fruit per plot. Factors of fruit quality including firmness, soluble solids, and size were evaluated from 2 10-fruit samples per plot at normal harvest maturity. Fruit and foliage were examined for phytotoxicity after each spray.

Pear, Insecticide Evaluations, 1991

Abstract Mature 'Bartlett' pear trees were sprayed with handguns operating at 600 psi to evaluate pesticides for control of pear pests. Plots consisted of 5 single-tree replicates in randomized block design. All treatments were applied 2 May and 26 Jun. Cold Power and Ray-Gard were also applied 10 May, 23 May, and 25 Jul. Treatments were evaluated for PP control by counts made at 2-wk intervals. Adult PP were counted from a 5 beating-tray sample per replication. PP nymphs were counted from a 50-leaf sample per replicate. Leaf samples consisted of the proximal leaf, distal leaf and 3 leaves from the middle of 10 terminal shoots. Leaves were brushed and resulting slides were examined under 10 × magnification. Fruit damage by insects and mites was rated according to US grade standards for fresh market Bartlett' pears on 2 samples of 25 mature fruit per replication. Factors of fruit quality including firmness, soluble solids, and size were evaluated from 2 10-fruit samples per replicate at normal harvest maturity. Fruit and foliage were examined for phytotoxicity after each spray.

Pear, Agri-Mek Timing Study, Orondo, 1991

Abstract Twenty-five-yr-old 'Bartlett' pear trees were sprayed with an air carrier sprayer to compare effectiveness of petal fall and second-generation timing of Agri-Mek for control of pear psylla. Plots consisted of half-acre unreplicated rectangles. The earlier treatment was applied 10 May, the later one 5 Jun. Additional sprays applied to the entire orchard during the growing season included Guthion 35% WP 2.5 lb/acre on 11 Jul and Guthion 35% WP 2 lb/acre plus Mitac 50% WP 3 lb/acre on 31 Jul. Treatments were evaluated for PP by counts made at 2-wk intervals. Adult samples consisted of 2 25-beating-tray samples per plot on each date. PP nymphs were counted from 2 50-leaf samples per plot. Leaf samples consisted of the proximal leaf, distal leaf, and 3 leaves from the middle of 10 terminal shoots. Leaves were brushed and resulting slides were examined under magnification. PP russet and other pest damage were rated according to US grade standards for fresh market 'Bartlett' pears on 100 mature fruit per plot. Factors of fruit quality including firmness, soluble solids, and size were evaluated from 4 10-fruit samples per replicate at normal harvest maturity. Fruit and foliage were examined for phytotoxicity after each spray.

Pear, Soft Pesticide Test, 1991

Abstract 'Bartlett' and 'Anjou' pears were sprayed with handgun or airblast equipment to compare seasonal programs of soft pesticides for control of insect and mite pests of pear and survival of beneficial arthropods. Plots consisted of 3 30-tree replicates in 3-row blocks. An untreated check was also included in the randomized block design. PP adults, PP predators, and parasite, Trechnites insidiosus, densities were monitored by limb-taps. PP nymphs were counted on 50-leaf samples per replication. Samples for first generation nymphs were collected from fruiting spurs, those for second and subsequent generations were collected from growing shoots. The proximal leaf, distal leaf, and 3 leaves from the middle were picked from each of 10 shoots. Leaves were processed with a leaf brushing machine and PP nymphs and mites were counted on 20% of the resulting slides under 10 x magnification. Pest damage to fruit was determined by examining 50 fruit per replication at harvest. Fruit firmness, size, and soluble solids content were compared on 2 10-fruit samples per replication. Treatment histories for the 3 programs are presented in the table.

Pear, Agri-Mek Timing Study, Wenatchee 1991

Abstract Eleven-yr-old 'Bartlett' and 'Anjou' pear trees were sprayed with an air carrier sprayer to compare effectiveness of petal fall and second-generation timing of Agri-Mek for control of pear psylla. Plots consisted of 2 replicates of 12 by 6 tree rectangles. Additional sprays applied to the entire orchard during the growing season included Guthion 35% WP 3 lb/acre on 17 Jul and Guthion 35% WP 2 lb plus Mitac 50% WP 3 lb/acre on 31 Jul. Treatments were evaluated for PP by counts made at 2-wk intervals. Adult PP were counted from a 25-beatingtray sample per replication. PP nymphs were counted from 2 50-leaf samples per replicate. Leaf samples consisted of the proximal leaf, distal leaf, and 3 leaves from the middle of 10 terminal shoots. Leaves were brushed and resulting slides were examined under magnification. PP russet was rated according to US grade standards for fresh market pears on 50 mature fruit per cultivar per replication. Factors of fruit quality including firmness, soluble solids, and size were evaluated from 2 10-fruit samples per replicate at normal harvest maturity. Fruit and foliage were examined for phytotoxicity after each spray.