Spray Dates Research Articles

Remote Sensing for Optimum Herbicide Application Date for Rabbitbrush

By virtue of area occupied, aggressive competitiveness after disturbance, and lack of preference by grazing or browsing animals, green rabbitbrush (Chrysothamnus viscidiflorus) ranks as one of the most important weedy shrubs on Intermountain rangelands (Tueller and Evans, 1969; Evans et al., 1973). Green rabbitbrush is relatively resistant to applications of phenoxy herbicides; and careful timing in relation to stage of growth, temperature, and soil moisture is needed, to obtain control with applications of 2,4-D [(2,4-dichlorophenoxy) acetic acid] (Hyder et al., 1962). The growth pattern of this deciduous shrub makes it difficult to predict the optimum date to spray (Young and Evans, 1974). Leaf buds burst in late winter, and optimum spray date follows roughly 2 months later. About 60% of the annual growth needed for optimum susceptibility to 2,4-D occurs in the last 2 weeks before the herbicide should be applied. The land manager is faced with a difficult timing problem, and must obtain his estimates of phenology from vast and often remote areas of variable elevation, topography, and soils. The collection of large sequential samples from inaccessible areas for technical interpretation is a natural application of remote sensing. Our purpose was to evaluate the use of color infrared aerial photography to predict optimum date for application of herbicides to control green rabbitbrush.

Gypsy Moth Control with Dimilin® Sprays Timed to Minimize Effects on the Parasite Apanteles melanoscelus12

Dimilin® (1-(4-chlorophenyl)-3-(2,6 difluorobenzoyl)-urea), an insect growth regulator, was applied by mist blower at 0.0078 lb AI/10 gal water to gypsy moth, blower at 0.0078 lb AI/10 gal water to gypsy moth, Lymantria dispar L., infested apple trees on 3 spray dates when gypsy moth larvae were in stadia 1 and 2, 2 and 3, and 3 and 4, respectively. Percent larval mortality was high on all 3 spray dates. The 1st spray resulted in decreased percent emergence of the larval parasite, Apanteles melunoscelus (Ratzeburg), from the gypsy moth host, while the 2nd and 3rd sprays did not. Six rates of Dimilin between 0.0078 and 0.00025 lb AI/10 gal water were applied similarly on May 29, 1975. Mortality data yielded a significant concentration-response curve for the gypsy moth with the higher rates being comparable in effectiveness to carbaryl at 0.5 lb AI/10 gal water. Residual activity of Dimilin was high for 2 weeks as opposed to one week for carbaryl.

Black Walnut Curculio Control, Missouri 1973-75

Abstract An experimental control program for the black walnut curculio was conducted over a three-year period in a 5-acre stand of mature black walnut located in Cedar County, Missouri. Initial spray dates for the first two years were established on adult emergence dates obtained from available literature. For the final year, the first spray date was based on emergence dates established through adult trapping. Spray dates in 1973 were May 15, May 30, and June 12; in 1974, May 30 and June 17; and in 1975, May 7, May 15, and June 11. Trees were selected and flagged to represent three spray groupings and one control group of five trees each in one block. Three such blocks were established for a total of 60 trees. The spray groups received applications of Guthion 2S, Benlate (WP), and a mixture of the two. Guthion was mixed at a rate of 24 oz/100 gal water. Benlate was mixed at 2 lb/100 gal of water. Eight tablespoons of Plyac a spreader-sticker were added to each 100 gallon formulation. Benlate was tested in an effort to reduce walnut anthracnose. When possible, spraying was done in the evening. At all times the wind was less than 10 mph with temperatures in the lower 70’s. Sprays were applied with a 150 gallon capacity Broyhill power sprayer the first year. The following two years a farm tractor carrying a 55 gallon drum with a PTO powered pump served as the spray unit. As nuts dropped they were collected and dissected for curculio larvae. Data were recorded as to presence or absence of larvae and total nuts collected per spray group.

Apple, P. Ulmi Seasonal Control, 1975

Abstract Test materials were applied to 10-year-old apple trees at Monmouth, Maine, at 5X concentration with an airblast sprayer operating at 100 psi and at the rate of 300 gallons per acre. Spray dates were May 8 (half-inch green), May 15, 23 (pink). May 27 (petal fall), June 9, 19, July 2, 16, and August 1 (fifth cover), and on July 16 and 24 for Kelthane. Insecticides which were applied separately to the test plots included Marlate 50W (3 lb/100 gal) on May 30 and June 9, Epsom salts (15 lb) on May 30, and Solubor (1 lb) on June 9; insecticides tank-mixed with test materials were Marlate 50W (3 lb/100 gal) on June 19, lead arsenate (2 lb) on July 2, 16 (no LA added to Benlate + oil mixture on July 16), Thiodan 50W (1 lb) on July 16, and Sevin 80W 0-25 |b) on August 1. Each treatment was applied to a block of 27-40 trees. From each tree of 2 Red Delicious, 1 Golden Delicious, and 1 Mcintosh cultivars per block, 25 leaves were collected mostly at chest-height around the periphery of the tree, brought into the laboratory, and brushed onto glass plates coated with a Tween 20-alcohol mixture; mites were counted the same day. Mite population pressure was very severe. Late July and August were very hot and dry.

Apple Insect and Mite Control, 1975

Abstract Test materials were applied to 15-year-old apple trees at Winthrop, Maine, as dilute sprays with a hand gun from a hydraulic sprayer operating at 250 psi and at a rate of 300 gallons per acre. Spray dates were May 30 (petal fall), June 9, 23, July 7, 22, August 4, and 18; each material was applied on all dates. The fungicide program consisted of Difolatan 4F (5 qt/ 100 gal) at half-inch green and Polyram 80W (2 lb/100 gal) at each cover; Polyram was tank-mixed with each treatment. There were 4 single-tree replications per treatment. A randomized complete block design was utilized with 1 Cortland and 3 Mcintosh cultivars per treatment in Test 1; and 2 Melba, 1 Golden Delicious, and 1 Mcintosh per treatment in Test 2. In Test 3, trees were selected in a 3 x 3 Latin Square design, with 3 Mcintosh per treatment. Except for the test trees, this orchard was unsprayed. On September 4, 3/4 box of apples was picked from each tree and ca. 300-500 apples were examined per treatment on September 6-12 for external egg punctures (apple maggot), egg-laying scars (plum curculio), and typical feeding injuries (codling moth and lesser appleworm). Apples with maggot egg punctures were sliced to determine success of egg hatch and/or of maggot survival (success indicated by a penetration of more than 1/4 inch). Evaluation of apple aphid control was based on a count of all live aphids found on the distal 4 unfurled and 1 furled leaves and on the stem included by these leaves on each of 10 terminal vegetative shoots located around the periphery of each tree at a height of 3-6 feet. All mines of the spotted tentiform leafminer which were found on 10 vegetative terminals selected at chest-height around the periphery of each tree were recorded. European red mites were counted on 25 leaves per tree (33 or 34 leaves per tree in Test 3) collected mostly at chest-height around the periphery of each tree. The leaves were brought into the laboratory and brushed onto glass plates coated with a Tween 20-alcohol mixture; mites were counted the same day. Fall webworm control was evaluated from estimates made on September 6 of the length of each and every web encompassing a branch and leaves of each tree. Except for European red mite, no pest populations exerted serious pressure.

Apple, P. Ulmi Early Control, 1975

Abstract Test materials were applied to apple trees at Monmouth, Maine, as dilute sprays with a hand gun from a hydraulic sprayer operating at 300 psi. In Tests 1 and 2, 10-year-old trees were sprayed at rates of 300 and 500 gallons per acre, respectively; in Test 3, 25-year-old trees were treated at 200 gallons per acre. Spray dates were May 9 (half-inch green). May 20 (pink), May 30 (petal fall), and June 10-11 (first cover). The standard pesticide program consisted of captan 80W (1.0-1.5 lb/100 gal) on 11 dates, Epsom salts (15 lb) on May 30, Solubor (1 lb) on June 10, Marlate 50W (3 lb) on May 30, June 10, and 23, and lead arsenate (2 lb) on July 3. There were no tank-mixtures of acaricides with other pesticides. There were 4 single-tree replications per treatment. A randomized complete block design was utilized with 1 Cortland (C) and 3 Red Delicious (RD) cultivars per treatment in Test 1; 1 Golden Delicious (GD), 1 Early Mcintosh, 1 RD, and 1 C per treatment in Test 2; and 1 RD and 3 GD per treatment in Test 3. From each tree, 25 leaves were collected mostly at chest height around the periphery of the tree, brought into the laboratory, and brushed onto glass plates coated with a Tween 20-alcohol mixture; mites were counted the same day. Mite population pressure was very severe. May and June were hot and dry except for unusually rainy weather the first 2 weeks of June.

Apple, P. Ulmi Summer Control, 1975

Abstract Test materials were applied to apple trees at Monmouth, Maine, as dilute sprays with a hand gun from a hydraulic sprayer operating at 250-300 psi. In Test 1, 25-year-old trees were sprayed at a rate of 250 gallons per acre; in Tests 2 and 3, 10-year-old trees were treated at 500 gallons per acre. Spray dates were July 10 and 18 (Tests 1 and 2) and July 28 and August 5 (Test 3); each material was applied on both dates. The fungicide and insecticide program during the course of these acaricide tests consisted of captan 80W (1 lb), Thiodan 50W (0.5 lb) and lead arsenate (2 lb/100 gal) on July 17, and Thylate 65W (1 lb) and Sevin 80W (1.25 lb/100 gal) on July 30. There were no tank-mixtures of acaricides with other pesticides. There were 4 single-tree replications per treat-ment. A randomized complete block design was utilized with 1 Red Delicious (RD) and 3 Golden Delicious (GD) cultivars per treatment in Test I; 1 Cortland (C) and 3 RD per treatment in Test 2; and 1 Early Mcintosh, 1 RD, 1 GD, and 1 C per treatment in Test 3. From each tree, 25 leaves were collected mostly at chest-height around the periphery of the tree, brought into the laboratory, and brushed onto glass plates coated with a Tween 20-alcohol mixture; mites were counted the same day. Mite population pressure was very severe. At the prespray date egg populations ranged from 20-35 eggs/leaf (Tests 1 and 2) or from 40-80 eggs/leaf (Test 3). Late July and August were hot and dry.

Apple, Test of Acaricides, 1973

Abstract Experimental sprays were applied to run-off to single-tree plots in a randomized block design with 2 replicates of Golden Delicious and 2 York Imperial. Treated single-trees were separated by others not sprayed with acaricides. Experi-mental sprays were applied with a John Bean sprayer, 35 gpm pump, equipped with a spray mast carrying 7 spray guns arranged to wet the uniformly trimmed trees. Spray dates for the test acaricides were: Replicates A and C only July 5 and 6 (Treatments Omite 6 E 118 ml and Vydate 4 EC 118 ml were not applied); on July 12 and 13 all treatments except Vydate were applied to all plots in all 4 replicates; a simi-lar spray was applied on August 15; Vydate spray dates were May 17, June 1, June 15, July 2, July 16, August 2, and August 20. Effec-tiveness of the test acaricides on the European red mite was assessed by counting the mites several times during the season on samples of 20 leaves/tree, 80/treatment. Until the last count of the season on August 23, mite counts for the York Imperial trees. Replicates A and C, and for the Golden Delicious trees. Replicates B and D, were kept separate. The count of twospotted spider mites, predatory mites: Amblyseiusfallacis, and Zetzelliamali on August 23 are shown as mites/100 leaves to make the differences between treatments more apparent. Apple aphid data were collected by counting the number of infested terminals out of 10/tree, 40/treatment. Also the number of infested leaves per infested terminal was counted and the average calculated. Aaverage temperatures were: June 71.30° F, July 73.32° F, and August 73.53° F. Rainfall in inches was: June 5.04, July 2.03, and August 4.57.

Apple, Insecticide Test, 1974

Abstract Experimental sprays were applied to run-off to single-tree plots in a randomized block design with 4 replicates of Golden Delicious. Treated single-trees were separated by others not sprayed with insecticides. Experimental sprays were applied with a John Bean sprayer, 35 gpm pump, equipped with a spray mast carrying 7 spray guns arranged to wet the uniformly trimmed trees. Spray dates for the test insecticides were: May 14, 30, June 13 (UC-49035 treatments dropped after June 13), June 27 and 28, July 19 and 20, and August 8. The fungicide mixture 1.5 lb captan 50W plus 1.5 lb Polyram 80W/acre was applied with an airblast sprayer on May 29, June 10 and 25, July 8 and 23, August 5 and 19. Average temperatures were: May 59.16° F, June 65.62° F, July 72.87° F, August 72.24°F, and September 63.23° F. Rainfall in inches was: May 3.31, June 5.05, July 1.56, August 2.73, and September 4.88. 1974 was a light crop year. Effectiveness of the insecticides on the codling moth-oriental fruit moth complex was evaluated by scoring for injury all drops after July 1 and a picked sample of 25 apples/replicate, 544/treatment taken on August 26, eighteen days after the last spray. Apple samples averaged 136/replicate, 544/treatment. Effectiveness of the insecticides on the European red mite and on Z.mali was determined by making counts of mites on samples of 20 leaves/tree, 80 leaves/treatment. Effect of the sprays on the predator S.punctum was evaluated by 3-min counts of larvae, pupae and adults around the periphery of the test trees. Effectiveness on apple aphids was determined by collecting 4 terminals from the top of the tree and 4\terminals from around the bottom of the tree. Then the number of aphids on the most infested leaf from each terminal was counted.

Apple, Test of Acaricides, 1975

Abstract Experimental sprays were applied to run-off to single-tree plots in a randomized block design with 2 replicates of Golden Delicious and 2 Red Delicious, buth spur-type trees. Experimental sprays were applied with a spray gun from a truck-mounted John Bean sprayer equipped with a 35 gpm pump. Spray dates for test acaricides were: June 3 for all treatments except S-15126, the 3 dosages of which were applied on June 10; the second spray of all treatments was applied on July 10. General purpose sprays of 0.75 lb captan 80W, 0.25 lb Guthion 50W, and 0.5 lb Sevin 50W/100 gallons dilute were applied at ca. intervals of two weeks throughout the summer. Average temperatures were: May 61.08° F, June 68.98° F, July 72.97° F, August 73.89° F and September 61.13° F. Rainfall in inches averaged: May 4.05, June 7.60, July 3.12, August 2.01 and September 13.84. Effectiveness of the test chemicals on the European red mite, twospotted spider mite and A.fallacis was evaluated by making several counts of mites on samples of 20 leaves/tree, 80 leaves/treatment.

Apple, Integrated Test, 1975

Abstract Several insecticide-acaricide programs were evaluated for insect control, mite suppression, and influence on the predator, Stethoruspunctum. Sprays were applied to 4-tree plots in a randomized block design with each plot consisting of a York Imperial, Red Delicious, Jonathan, and Stayman Winesap. Each treatment was replicated 4 times. Treated plots were separated by others not sprayed with insecticides. Treatments were applied as 6X concentrates with a Friend Airmaster 393 sprayer at 25 gpa/alternate side spray driven at 2 mph. Spray dates for insecticides-fungicides were: May 20 and 27; June 4, 11, 18 and 25; July 2, 9, 16, 23 and 30; August 7, 13, 20 and 27; and September 3. Polyram 80W, 2.0 lb/acre and sulfur 95W, 1.5 lb/acre were applied to all plots except the Dikar plot from May 20 to June 11; captan 50W, 1.5 lb/acre and sulfur at the same rate above were applied from June 18 to July 16; and captan by itself at the above rate was applied after July 16. Zolone 25W, 10 oz/acre was substituted for the rate listed in all plots receiving the Guthion-Zolone combination except the Dikar plot from June 18 to July 30. Lannate 25W, 0.25 lb/acre was applied only on July 2, 9, 16 and 23; the rate was changed to 0.5 lb/acre on July 30, August 7, 13, 20 and 27. Thiodan 50W, 1.0 lb/acre was applied on June 18 and 25 to all plots. Plictran 50W, 2 oz/acre was applied with the first 4 treatments on July 3 to stabilize the mite populations. Effectiveness of the treatments on fruit feeders was assessed by scoring for injury all drops from the variety Stayman Winesap after July 1 and a picked sample 14 days after the last spray. Apple samples averaged 121/replicate and 484/treatment. Effectiveness on the white apple leafhopper was evaluated by counting nymphs on the underside of 25 leaves/tree, 2 trees/replicate for both generations. Effectiveness of treatments on the European red mite was evaluated by counting the mites several times during the season on samples of 20 leaves/replicate (Stayman Winesap only), 80 leaves/treatment. The effect of sprays on the predator S.punctum was evaluated by 3 minute counts of adults and larvae around the periphery of the test trees (Stayman Winesap and York Imperial). May 61.08°F, June 68.98° F, July 72.97° F, August 73.89° F, and September 61.13° F. Rainfall in inches averaged: May 4.05, June 7.60, July 3.12, August 2.01 and September 13.8.

Apple, Test of Acaricides, 1974

Abstract Experimental sprays were applied to run-off to single-tree plots in a randomized block design with 2 replicates of Golden Delicious and 2 York Imperial. Treated single-trees were separated by others not sprayed with acaricides. Experi-mental sprays were applied with a John Bean sprayer, 35 gpm pump, equipped with a spray mast carrying 7 spray guns arranged to wet the uniformly trimmed trees. Spray dates for the test acaricides were: July 1, July 9 (4 lb NC 13292 25W dropped), and August 13. Effectiveness of the test acaricides on the European red mite was assessed by counting the mites several times during the season on samples of 20 leaves/tree, 80/treatment. Counts of the European red mite are presented as the average number of mites per leaf. Counts of the twospotted spider mite, A.fallacis and Z.mali are presented as the number of mites per 100 leaves to make differences between treatments more apparent. Average temperatures were: May 59.16° F, June 65.62° F, July 72.87° F, August 72.24° F and September 63.23° F. Rainfall in inches averaged: May 3.31, June 5.05, July 1.56, August 2.73, and September 4.88. General sprays involving captan, Polyram, Guthion and Sevin were applied as 6X concentrates with an airblast sprayer to the whole experimental block at ca. two-week intervals.

Apple, Test of Insecticides, 1973

Abstract Experimental sprays were applied to run-off to single-tree plots in a randomized block design with 3 replicates of Golden Delicious and 2 York Imperial. Treated single-trees were separated by others not sprayed with insecticides. Experimental sprays were applied with a John Bean sprayer, 35 gpm pump, equipped with a spray mast carrying 7 spray guns arranged to wet the uniformly trimmed trees. Spray dates for test insecticides were: May 17, May 31 (June 1 for diazinon), June 15, July 2 and 16, August 2 and 20. During May, June and July, 2 lb Polyram 80W/acre was applied to the whole block at ca. 2 week intervals with an airblastsprayer; in August 2 sprays of 1 lb captan 80W plus 1 lb Polyram 80W/acre were applied similarly. Average temperatures were: May 56.63° F, June 71.30°F, July 73.32°F, and August 73.53°F. Rainfall in inches was: May 6.24, June 5.04, July 2.03, and August 4.57. Effecti veness of test chemicals on the European red mite was evaluated by making 3 counts of mites on samples of 20 leaves/tree, 100 leaves/treatment. The effect of sprays on the predator Stethoruspunctum was evaluated by 3 minute counts of adults and larvae around the periphery of the test trees. Effectiveness of chemicals on fruit feeders was evaluated by scoring for injury all drops after July 1 and a picked sample 15 days after the last spray from 3 replicates of Golden Delicious and 2 replicates of York Imperial. Apple samples averaged 239 fruits/replicate and 1,195/ treatment. Effectiveness on the white apple leafhopper was evaluated by counting numphs on the underside of the leaves for both generations; on the apple aphid by counting the number of infested terminals/10 terminals/tree and calculating the percent infested. Another method was to count the number of aphid infested leaves/terminal.

Apple, Test of Insecticides, 1975

Abstract Experimental sprays were applied to run-off to single-tree plots in a randomized block design with 2 replicates of York Imperial and 2 Golden Delicious. Treated single-trees were separated by others not sprayed with insecticides. Experimental sprays were applied with a John Bean sprayer, 35 gpm pump, equipped with a spray mast carrying 7 spray guns arranged to wet the uniformly trimmed trees. Spray dates for the test insecticides were: June 2, 16, 30 and July 1, 15, and 28, August 11 and 25; Pirimor was applied only on June 2, July 25 and August 11; Dimilin was applied only on June 2, June 30, July 28 and August 25; S-15126 was applied only on August 11 and 25 after Stethoruspunctum populations were established in the trees. The following special sprays were applied to the test trees: June 13, Phosphamidon 8, 8 fl oz/100 gal (6X concentrate) with an airblast sprayer; June 19, Systox 6, 4 fl oz/100 gal (IX dilute) with a spray gun; August 14 Plictran 50W, 8 oz/100 gal (6X concentrate) with an airblast sprayer (East of tree's side only). During May, June, July and August, general sprays involving captan and sulfur were applied as 6X concentrates with an airblast sprayer to the whole experimental block at ca. 2 week intervals. Average temperatures were: May 61.08° F, June 68.98° F, July 72.97° F, August 73.89°F, and September 61.13° F. Rainfall in inches averaged: May 4.05, June 7.60, July 3.12, August 2.01 and September 13.84. Effectiveness of test chemicals on the European red mite was evaluated by counting the mites several times during the season on samples of 15 leaves/tree, 60 leaves/treatment. The effect of sprays on the predator S.punctum was evaluated by 3 minute counts of adults and larvae around the periphery of the test trees. Effectiveness of chemicals on fruit feeders was assessed by scoring for injury all drops after July 1 and a picked sample 14 days after the last spray. Apple samples averaged 230 fruits/replicate and 920/treahnent. Effectiveness on the white apple leafhopper was evaluated by counting nymphs on the underside of 25 leaves/replicate for both generations; on the apple aphid by counting the number of infested terminals/10 terminals/tree and calculating the percent infested. The number of aphid infested leaves/terminal was also determined. The effectiveness of the test materials on the rosy apple aphid was assessed by collecting 10 infested clusters/replicate and determining the percent infested leaves/cluster, the percent leaves with 1-10 live aphids, and the percent leaves with 11 or more live aphids.

Ascospore discharge in Drepanopeziza punctiformis in relation to infection of some poplar clones

Ten years study of the discharge of ascospores is described. As the discharge started each year before the first flushing leaves reached the susceptible stage, growers can determine the best date of the first spraying simply from the ing stage of the host. Radio warnings based on the first date of ascospore discharge are superfluous.

The Influence of Succinic Acid-2,2-dime thy lhydrazide on Peach Quality1,2

Abstract Succinic acid -2,2-dimethylhydrazide (Alar) was applied at various postbloom spray intervals and concentrations to ‘Ranger’ peaches from 1965 to 1969 and to ‘Cardinal’ and ‘Blake’ peaces in 1969. Fruit of each cultivar was harvested at a uniform firmness to determine the influence of Alar on quality attributes not directly associated with changes in fruit maturity. Color attributes, particularly flesh color, were enhanced by Alar over a wide range of spray dates to a much greater degree than other quality attributes at a given maturity. The results indicated a stimulation of anthocyanin biosynthesis by Alar without a corresponding effect on other attributes normally considered to be indicators of physiological maturity.

Spray Date Effects on Behavior of Herbicides on Brush

Dicamba (3,6-dichloro-o-anisic acid), 1,1′-dimethyl-4,4′-dipyridinium ion (paraquat), and (2,4,5-trichlorophenoxy)-acetic acid (2,4,5-T) were applied as foliar sprays to 4-year-old sweetgum (Liquidambar styraciflua L.), green ash (Fraxinus pennsylvanica Marsh.), water oak (Quercus nigra L.), and loblolly pine (Pinus taeda L.). For the three hardwood species the amount of herbicide absorbed and translocated, as measured 4 days after application, was correlated closely with tops killed 1 year later. Applications in May were more effective than those made later in the growing season. Loblolly pine was defoliated by all herbicides but recovered the second season after spraying.

Herbicide Treatment of Browse on a Big-Game Winter Range in Northern Idaho

2,4-D; 2,4,5-T, and a mixture of these two chemicals were tested for effectiveness in lowering the live crown and increasing the basal sprouting of browse grown beyond the reach of elk and deer. Concentrations of 3/, 11/2, and 3 lb acid equivalent per acre were applied by helicopter in late June. Date of spraying was studied separately. The mixture at 3 lb per acre was most effective in killing aerial crowns. Rocky Mountain maple (Acer glabrum) was relatively resistant to these sprays; Scouler willow (Salix scouleriana), Saskatoon serviceberry (Amelanchier alnifolia), creambush rockspirea (Holodiscus discolor), and bitter cherry (Prunus emarginata) were moderately sensitive; redstem ceanothus (Ceanothus sanguineus), and Lewis mockorange (Philadelphus lewivsi) were very sensitive. Willow sprouted prolifically; rockspirea and maple sprouted moderately; ceanothus and mockorange sprouted poorly. Species differed considerably in reaction to date of spraying. Early summer and late summer spraying were usually more effective than midsummer spraying; however, the study revealed no seasonal pattern that could be used as a general guide for spraying to achieve optimum effectiveness in browse rehabilitation. Limitations governing present use of these herbicides for browse improvement in northern Idaho should be noted carefully. Only cautious use of spraying is proposed. Much of northern Idaho's winter range for elk and deer is unique in two respects. First, it consists of seral shrub fields that have resulted from wildfires or logging in coniferous timber stands; the natural succession is toward closed conifer stands that produce little palatable browse. Second, many browse species grow tall beyond the reach of elk and deer. Important among these are willow, serviceberry, maple, and bitter cherry. Once the shrub crowns extend above the animal's reach, the shrubs continue to occupy the site fully but produce very little available browse. This condition prevails especially on elk winter ranges along the Lochsa and Selway Rivers. Reversion of much former winter range to conifers increases the need for maintaining maximum browse production on areas designated specifically as big-game winter range. In part, this means restoring to usable production all plants too tall for the animals' use. Cutting, burning, and using herbicides have all been considered as possible methods to kill back old growth and stimulate sprouting of tall-growing browse species. Cutting appears effective, but it requires using manual labor on steep slopes; this is expensive-approximately $107 per acre in 1962. (Cost of $87 in 1950, reported in files of Clearwater National Forest, is adjusted here to 1962 level using U. S. Bureau of Labor Statistics index of wages for lumber and wood products.) Burning over such steep slopes is risky because of the soil erosion potential and problems of fire control. Aerial application of a suitable herbicide would avoid the objectionable features of the other two methods. Herbicides are being used extensively elsewhere for controlling brush. Usually the objective is complete kill rather than only top kill intended to induce basal sprouting. Until recently, the effects of herbicides on northern Idaho browse species have received little attention. DeJarnette et al. (Preliminary report of spraying ribes and brush with 2,4,5-T by helicopter in the western white pine region. U. S. Forest Service, Region 1, Serial 144. 14pp. (Processed.) 1949) achieved at least 75 percent top kill of Salix sp., Amelanchier florida, Acer glabrum, and Ceanothus velu-

Field Insecticide Tests for Alfalfa Weevil and Pea Aphid

Seven insecticides, including two new systemics, were tested against the alfalfa weevil, Hypera poslica (Gyll.), and the pea aphid, Macrosiphum pisi (Harris), in randomized, replicated field plots. Materials used and rates of application are included. April 30 was the spray date. Results were obtained by sampling insects with an insect net, May 9, 16, and 29, The percentage of control, or reduction of infestation, was obtained for each material for each date. The new systemics, American Cyanamid Company Compound 12880 ( O,O -dimethyl- S -(N-methylocarbamoylmethyl) phosphorodithioate) and Compound 18706 ( O,O -dimethyl- S -(N-ethylcarbamoylmethyl) phosphorodithioate), showed promising results against the pea aphid (97% reduction in numbers 16 days after treatment). These chemicals gave a quick reduction of alfalfa weevil adults (98% and 96% control at the 9-day sampling), and Compound 12880 substantially reduced the weevil larvae for the same period. All materials except Compound 18706 produced some chlorosis in the alfalfa; however, Compound 12880 produced only a negligible amount. Guthion® ( O,O -dimethyl S -( 4-oxo-3 H -1, 2,3,-benzotriazine-3-methyl) phosphorodithioate) performed well against both pea aphid (89% control at the 16-day sampling) and the alfalfa weevil, at 9 days. None of the test materials at the dosages used appeared ns effective against alfalfa weevil as heptachlor combined with malathion.

Effect of Spray Date on Residues of Chlorinated Hydrocarbon Insecticides on Peaches1

Effect of Spray Date on Residues of Chlorinated Hydrocarbon Insecticides on Peaches1