Field Comparisons of Insecticides for Control of the Codling Moth,Cydia Pomonella (L.), with Observations on Effects of Treatments on Mite Populations

In field trials carried out from 1956 to 1958 various insecticides were compared with DDT and lead arsenate to assess their efficiency against codling moth. In each trial sprays were applied to replicated single-tree plots in late June and again three to four weeks later.

Against codling moth, 0.04% azinphos-methyl and 0.1% Sevin were as effective as 0.1% DDT, and all three were more effective than 0.2% lead arsenate; 0.6% ryania was as effective as 0.2% lead arsenate but was less effective than 0.1% DDT. In a single trial 0.02% diazinon gave control comparable with that given by 0.1% DDT. In 1958, damage caused by larvae of the partial second generation, which began to hatch about six weeks after application of the second spray, was significantly reduced by DDT and Sevin, but not by azinphos-methyl or lead arsenate. Laboratory tests of the toxicity to young larvae of fresh and field-weathered deposits on fruit gave results consistent with those obtained in the field trials.

Populations of the fruit tree red spider mite increased considerably on trees treated with DDT or Sevin, and smaller but significant increases were observed after treatment with diazinon and, in some trials, ryania. Lead arsenate had little or no effect on mite populations, and azinphosmethyl gave control of mites for two to three months.     

A comparison of high- and low-volume spray techniques in the thinning of ‘Golden Delicious’ apples

A trial at the Grove Research Station, southern Tasmania in 1989-90 examined the thinning of mature ‘Golden Delicious’ apple trees. High-volume sprays were applied at 6,0001 ha^-1 as air blast or vertical boom using NAA at 10mg l^-1 4d after full bloom (AFB) and 18 d AFB. Carbaryl at 1,000 mg l^-1 and thiram at 1200 mg l^-1 were also applied as combined sprays, 30 and 38 d AFB. These high-volume sprays were compared with unsprayed controls and Micron and Micronair low volume sprayers at 200 and 1,1000 l ha^-1. The dosages of the low volume applications were equilibrated to apply the same rates of chemical per hectare as the high-volume sprays, and the timing was the same. All spray treatments reduced crop load to acceptable levels when compared with the overcropped controls. There were no consistent differences between treatments for number of fruit per cm² limb area except that the lowest volume Micron spray thinned significantly less than most other treatments. Considering the number of fruit per 100 blossom clusters the airblast spray was the only treatment to be significantly better than the Micron at 2001 ha^-1. These numbers were reflected in mean fruit weight with the control fruit being significantly lighter than any sprayed fruit. The air blast treatment produced significantly heavier fruit than all other treatments, apart from the other high volume treatment. Fruit size distribution (FSD) showed significant differences between the control and all the spray treatments. The airblast treatment produced significantly more fruit in the 80 mm or larger category than all treatments, apart from the vertical boom application. These preliminary results suggest that although low-volume sprays can thin apple trees, the use of ultra low volumes (ULV) should be explored using machines capable of controlled droplet application (CDA). This may ultimately lead to less chemical being applied per hectare.     

Evaluation of organic,synthetic and physical insecticides for the control of horse chestnut leaf miner (Cameraria ohridella)

Two separate trials during 2007 and 2008 were conducted using containerized white flowering horse chestnut trees (Aesculus hippocastanum L.) to assess the efficacy of a range of insecticides applied at three different times during a growing season against the insect pest, horse chestnut leaf miner (Cameraria ohridella Deschka and Dimic; HCLM). Insecticides were timed to coincide with the emergence of the adult moth, the target organism. A conventional synthetic insecticide (deltamethrin) used within the UK for HCLM control was included for comparison. A marked impact of insecticide type and frequency of application on HCLM severity was recorded. The effectiveness of each insecticide on mean number of HCLM mines per leaf and percent HCLM larvae/pupae mortality increased when applied at increasing frequencies, i.e. three sprays provided a higher degree of control than two sprays while two sprays provided a higher degree of control than one spray. Limited efficacy as HCLM protectant compounds was demonstrated when the insecticides pyrethrum and soap were applied, irrespective of number of applications. The synthetic insecticide deltamethrin and insect growth regulator diflubenzuron provided the greatest degree of HCLM control. In some instances two foliar sprays provided 100% HCLM control. Efficacy of remaining insecticides based on reduction of HCLM mines per leaf after three sprays averaged across both the 2007 and 2008 trials was in the order silicon dioxide > alginate/polysaccharide combination > organic plant extract > spray oil. Results show commercially registered insecticides exist that provide growing season control of HCLM provided two sprays are applied.     

Field spray trials for control of the strawberry mite,Tarsonemus fragariae (Zimm.)

Results are given of field trials in which various chemical sprays were tested for control of the strawberry mite Tarsonemus fragariae. Activity of most compounds was poor, although promising results were obtained with Bayer 5024 (methiocarb), Boots BTS 27419, Du Pont 1642 and Shell WL 21959 (‘Talcord’). None gave as good control as a standard endosulfan spray, but some results were better than those achieved with a standard application of dicofol.     

Routine Versus Post-Infection Sprays Against Apple Scab on Cox’s Orange Pippin

Routine sprays applied at regular intervals against apple scab on open-centred bush Cox’s Orange Pippin trees on M.IX rootstock were compared with curative sprays promptly applied after infection periods, as defined in terms of the Mills chart from instrument readings. A total saving of ten applications resulted from curative treatment over seven consecutive seasons. Routine interpretation of instrument data failed in only one marginal instance to detect an infection period, which arose from discontinuous wetting, but thereby jeopardized curative control in one season (1963).

With the one exception, both methods gave a high degree of scab control every year, although infection on the unsprayed controls was often severe. Some spray damage occurred in the form of reduced cropping or fruit russeting, particularly from phenylmercury chloride and didecyldimethyl-ammonium bromide as curative sprays, and from lime-sulphur applied post-blossom, either curatively or as routine. Captan with DNOPC (“dinocap”), however, gave superior crops showing relatively light russeting, and dodine acetate proved generally safe.

Although curative spraying proved generally successful on these relatively small, open trees, its exclusive use on an extensive scale is problematic. A feasible compromise is to reinforce a basic routine with curative sprays when desirable.     

The influence of systemic inducing agents on horse chestnut leaf miner (Cameraria ohridella) severity in white flowering horse chestnut (Aesculus hoppicastanum L.)

Two separate trials during 2010 and 2011 were conducted using field grown white flowering horse chestnut trees (Aesculus hippocastanum L.) to asssess the insecticidal efficacy of three systemic inducing agents (SIR), namely (Messanger (active substance (a.s.) Harpin protein), Phoenix (a.s. Potassium phosphite) and Rigel (a.s. Salicylic acid derivative) applied to coincide with the appearance of each adult generation of the insect pest, horse chestnut leaf miner (Cameraria ohridella Deschka and Dimic; HCLM). A conventional synthetic insecticide (deltamethrin) used within the UK for HCLM control was included for comparison. A marked impact of SIR inducing agent and frequency of application on HCLM severity was recorded. The effectiveness of each SIR inducing agent on mean number of HCLM mines per leaf and percent HCLM larvae/pupae mortality increased when applied at increasing frequencies i.e. three sprays provided greater control than two sprays while two sprays provided greater control than one spray. The synthetic insecticide deltamethrin provided the greatest degree of HCLM control with two foliar sprays providing 100% HCLM control. Efficacy of SIR inducing agents based on reduction of HCLM mines per leaf after three sprays averaged across both the 2010 and 2011 growing seasons was in the order potassium phosphite > salicylic acid derivative > harpin protein > water control where leaf mining activity was reduced by 35–64%. Enhancement of leaf phenolic content was indicated as a means by which SIR agents reduced leaf mining activity. Results show commercially available SIR inducing agents exist that provide potentially acceptable degrees of HCLM control provided at least two sprays are applied during a growing season.     

The Response of Magnesium-Deficient Edward VII Apple Trees to Variations in the Timing and Composition of Foliar Sprays

Magnesium-deficient Edward VII apple trees were used to study the effect of pre-blossom sprays of magnesium sulphate and urea, and to compare the efficiency of post-blossom sprays of magnesium sulphate and chloride.

Two pre-blossom sprays of 2% Epsom salt (MgSO_4·7H,O) prevented the development of early-season magnesium deficiency symptoms but did not increase fruit set. Similar sprays of 0· 5%urea had no effect on symptoms but increased the set of fruit.

Five post-blossom sprays of 2% Epsom salt largely eliminated both early and late symptoms and produced consistent increases in the magnesium content of the leaves (% dry wt.). There was also a large increase in crop, due mainly to a greater fruit set which could be detected after the second spray application. Growth responses also were associated with this treatment.

Five post-blossom sprays of 0·83% magnesium chloride, i.e. containing only half the amount of magnesium, produced similar responses, except that growth was not affected. Reducing the number of magnesium chloride sprays to three, but applying them over the same time interval, resulted in similar' crop responses even though less magnesium was taken up and symptoms were slightly less effectively controlled.     

硝酸钙和IAA对温州蜜柑果实钙含量及其品质的影响

在花期、花后1周、3周、采前2周对龟井蜜柑进行Ca(NO3)2、IAA和IAA+Ca(NO3)2喷布处理,同时测定了不同发育时期各处理果实钙含量及其采后果实的主要品质,并与采后浸钙处理和完熟采收果实品质进行了对比分析,结果表明:1)各处理的果皮钙含量在花后51d和112d均有所提高,但此期整个果实钙含量并无显著性差异,采收时各处理整个果实和果肉钙含量均显著高于对照;2)采收时各处理果实的可溶性固形物和可滴定酸均显著低于对照,可溶性糖、单果重、果皮色差值和相对电导率与对照无显著性差异,各处理糖酸比显著高于对照;3)采后30d时IAA+Ca(NO3)2喷布和采后浸钙处理果实的维生素C及完熟采收果实的可溶性固形物和可溶性糖均显著高于对照和其他处理。     

The interaction of Cytolin and NAA on cropping red ‘Delicious’ apple

A trial, at Spreyton in north-western Tasmania, studied the effects of Cytolin and NAA sprays on the thinning and shape of ‘Delicious’ apples. Untreated control and hand thinned trees were compared with trees treated with Cytolin or NAA alone, or in combination. Cytolin was applied at 25 mg 1~‘ at the king petal (KP) stage. NAA was applied at 8 mg I“1 at full bloom (FB) and 7,10, or 15 days after full bloom (AFB). Cytolin alone had no effect on thinning, fruit weight or on pip numbers but it did improve fruit shape. The combination of cytolin and NAA at FB overthinned. Cytolin and NAA combinations applied at all times after FB significantly decreased both mean fruit weight and pip numbers and reduced the percentage of fruit > 70 mm. All Cytolin-NAA combinations and the NAA treatments applied at 10 and 15 days AFB resulted in unacceptably high percentages of apples < 45 mm in diameter (pygmy fruit). It is recommended that Cytolin and NAA should not be used in the same spray programme. NAA alone is a most effective thinner at FB or seven days AFB.     

Flowering and fruiting in ‘Patterson’ apricot (Prunus armeniaca) in response to postharvest application of gibberellic acid

In July or August of 1988 and 1989 which was approximately 2 or 6 weeks, respectively, after fruit harvest, cultivar ‘Patterson’ apricot (Prunus armeniaca) trees were sprayed with a single spray of either 10, 50 or 100 p.p.m. gibberellic acid (gibberellin A₃, GA). GA sprays of 100 p.p.m. applied in early July reduced flower number per centimeter of limb length in the year following treatment. Flower number per centimeter of limb circumference was reduced by sprays of 50 and 100 p.p.m. GA applied in July. Fruit set was not affected by GA sprays. The yield and fruit number of hand thinned trees was equivalent to that found on trees treated with 50 and 100 p.p.m. GA sprays in July. Individual fruit weight (size) was increased by GA sprays of 50 and 100 p.p.m. in July compared to hand thinned trees. Fruit maturity was advanced when yields were reduced by GA sprays. In July, GA sprays of 10 p.p.m. resulted in increased individual fruit weight without reduced total yields per tree compared to non-thinned control trees. Results showed that the use of GA sprays the year before flowering (July) decreased flower numbers, eliminating the need for chemical or hand fruit thinning of ‘Patterson’ apricot.     

Field control of strawberry fruit rot (Botrytis cinerea Fr.,) by fungicides (II)

Fungicide trials against strawberry fruit rot (Botrytis cinerea Fr.) were conducted in 1968, 1969 and 1970 on cv. Cambridge Favourite. Dichlofluanid was applied at 6 lb a.i./acre/year (6.72 kg/ha), tetrachloroisophthalonitrile at 7.5 lb a.i./acre/ year (8.41 kg/ha) and benomyl at 1.5 lb a.i./acre/year (1.68 kg/ha). The first spray was applied when two or three flowers per plant had opened, and one, two or three subsequent applications were made at approximately 10-day intervals. Three or four applications gave better control than two.

Application of any of the three fungicides reduced fruit rot and resulted in improved yield. Benomyl and tetrachloroisophthalonitrile caused malformation of fewer fruits than dichlofluanid.     

The Effect of Lime-Sulphur Sprays Applied at Different Times in the Season on the Extension Growth of an Apple Rootstock

On four occasions during April and May 2% lime-sulphur was sprayed “to run-off ” on maiden M.IV apple rootstocks. The weight of the subsequent extension growth was recorded and the damage resulting from the sprays calculated. It was shown that the damage done by a spray varied according to the date of application, that the plants did not recover from this damage, that the interaction between pairs of sprays was in general non-significant but that certain specific interactions occurred. The interaction between the fungicide and fungus on the growth of the host is discussed.     

Preliminary studies on the use of (2RS, 3RS)-paclobutrazol for fruitlet thinning and growth control of ‘Conference’ pear

Summary

Single foliar sprays of paclobutrazol (PP333) at 300, 1000 or 3000 mg H applied at three different stages from full bloom to petal-fall in a year of average initial sets . and fruit size were equally effective in thinning ‘Conference’ pear, increasing the proportion of large fruits at harvest, but decreasing their absolute numbers. Sprays applied nine days after petal-fall reduced initial sets less effectively and, applied 21 days after petal-fall, were ineffective. Thinning was completed within 25 days after petal-fall. Shoot extension was initially retarded at all three concentrations, but later increased, so that the total growth made during the season was not reduced. Single foliar sprays at 300 or 1000 mg l^?1 applied at 70% full bloom in a year of heavy set and small fruit size increased the numbers of large fruits in the >55 mm size category by 66% and decreased those of fruits <55 mm by a similar amount. The increase in the yield of fruits >55 mm and decrease of unsaleable <45 mm fruits was equivalent to about 3 and 2 t ha^?1 respectively from a total average yield of about 17.5 t ha^?1. In the same experiment, similar sprays counteracted the stimulation in the production of small fruits by sprays of gibberellic acid (GA) applied on the same day, but did not increase the harvest of large fruits. Sprays of paclobutrazol at 30 or 100 mg l^?1 applied two weeks after petal-fall and then on three successive occasions at two-week intervals inhibited total extension growth per shoot during the season without affecting initial or final sets, fruit size or flower bud production. Single sprays applied at 100 mg l?1 in July reduced total extension per shoot almost as effectively as the repeated sprays. For more effective control of ‘Conference’ shoot growth, paclobutrazol may have to be sprayed later in the season than commercially recommended. Applied as a blossom thinner, paclobutrazol may increase the yield of large fruits only in years of heavy set and small fruit size, requiring that applications be delayed until set can be judged.     

Yield benefits associated with pre-blossom low-biuret urea sprays on Citrus spp.

Summary

This study evaluated the potential yield benefits of pre-blossom urea sprays on various Citrus spp. and to ascertain whether these yield benefits are as a result of altering the blossom composition or of supplying readily utilizable N during the critical flowering/fruit set period. Pre-blossom low-biuret urea sprays, 6–8 weeks before anthesis, at 1% concentration, one or two sprays 10–14 d apart, have resulted in significant (P<0.05) yield benefits in certain orchards. Experiments were conducted over a period of 2–4 years. Cultivars evaluated included ‘Shamouti’ oranges, ‘Ellendale’ tangor and ‘Minneola’ tángelo. In orchards where the leaf N level was below optimum the results were most significant while only slight or no yield responses were obtained in orchards where N levels approximated or exceeded 2.6%. Endogenous leaf ammonia levels were significantly increased for 14–30 d after the spray. This indicated a beneficial N level during the critical flowering and fruit set period. Because of large field variation no consistent trend with respect to the effect of the urea spray on changing the blossom composition (leafless vs. leafy inflorescences) could be demonstrated. Despite the increased ammonia levels recorded, no longer term increases in reserve leaf N levels were obtained.     

The Effect of Frequent Spraying with Calcium Nitrate Solutions on the Mineral Composition and the Occurrence of Bitter Pit of the Apple Cox’s Orange Pippin

In several commercial orchards the percentages of Ca and K in the leaves and fruit of the cultivar Cox’s Orange Pippin were determined at intervals during one or more years. The values for a series of untreated trees were continually compared with those of a comparable series of trees which were sprayed at about seven-day intervals with a Ca(NO₃)₂ solution. At the end of each experiment the fruit was placed in storage and later examined for the incidence of bitter pit.

The Ca contents of leaves and fruit and the quotient (K+Mg)/Ca in the leaves of untreated trees showed only a moderate relationship with the percentage of bitter pit. The K content of the fruit was more closely correlated, however.

The level above which much bitter pit was unlikely to occur was found to be approximately 7.5–8 mg Ca in a fruit of 140 g fresh weight.

The total amount of Ca in the untreated fruit increased in a rather regular and comparable fashion in the various experiments. The rate of increase was somewhat higher during the first period of development, until the fruit reached about 20–40 g in weight, than during its subsequent growth.

Spray treatments increased the Ca content of the leaves by 0.2–0.5% of the dry weight; a maximum of 4 mg Ca was added to the fruit, an increase of 47% on the basis of the amount already present. In general the Ca level increased progressively during the season with successive spray applications, and 9–15 sprays reduced bitter pit incidence to about 5%.

The permeability of the fruit tissue to ions diminished as a result of the sprays, and it is suggested that an increase in cell membrane permeability may be involved in the development of the disease.

For commercial orchards, more frequent sprays may need to be applied than are recommended at present to provide effective control of bitter pit.     

Field control of strawberry fruit-rot (Botrytis cinerea Fr.) by fungicides

Dichlofluanid effectively controlled strawberry fruit rot (Botrytis cinerea Fr.) in a series of field experiments from 1965 to 1967. Less than 1 % of fruits were infected where 6 lb./acre/year was applied in three sprays (0·1 % a.i. w./w.) at early flower, main flower and late flower stages. Less mildew (Sphaerotheca alchemillae (Grev.) Junnell) developed on fruits of cv. Royal Sovereign after sprays of dichlofluanid than after thiram or difolatan.

Yield of sound fruit was increased by all three fungicides; on cv. Talisman the yield was greatest with dichlofluanid and on cv. Royal Sovereign with thiram. Fruits of Royal Sovereign were damaged by dichlofluanid and to a lesser extent by thiram; the fruits were smaller and more of them were malformed, relative to the unsprayed plants. The fruits of Talisman were undamaged by the standard rates of thiram and dichlofluanid.     

A Lethal Virus Disease of Lloyd George Raspberry in Scotland

Trials lasting nine years have been conducted on two types of magnesium- deficient apple rootstocks to assess the curative value of foliar sprays and/or soil applications of Epsom salt (MgS0₄.7H₂0).

After the first year, M.IV rootstocks sprayed with 2% Epsom salt solution produced more, larger, and better-rooted shoots than did the untreated plants, giving more than a 60% increase in numbers of high-quality rooted shoots, and three sprayings were as effective as nine. The implications of this finding are discussed.

In contrast to M.IV, spraying MM.102 rootstocks did not lead to a sustained improvement in quality of rooted shoots even though symptoms of magnesium deficiency were eliminated and the number of shoots increased. Elimination of foliar symptoms is therefore, of itself, no indication of economic improvements of growth. It is concluded that some other factor, perhaps potassium deficiency, limited growth.

Foliar sprays applied nine times annually to M.IV rootstocks raised the percentage of magnesium in the leaves in successive years and eliminated symptoms typical of magnesium deficiency. With only three sprays annually, the magnesium concentration in leaves was also increased, but to a less extent and not until after the second year ; the symptoms were reduced in severity but not eliminated. The percentage of potassium in the leaves fell as the percentage of magnesium rose.

Soil applications at the rate of 46 cwt. per acre spread over eight years markedly increased " available ” magnesium in the top 3 ft. of soil, but produced only small increases in the percentage of magnesium in the leaves. Symptoms were only slightly reduced and there was little increase in growth. Thus, under the conditions of this experiment, soil treatment with Epsom salt was ineffective in curing magnesium deficiency.     

Interactions between hormonal and developmental signalling in the prevention of side-shoots in rose (Rosa hybrida L.)

Summary

This study investigated the effects of auxin sprays on the development of side-shoots in rose (Rosa hybrida L.). The rationale was to prevent or to minimise side-shoot development in a commercially acceptable rose cultivar. Equallyspaced doses (at 0, 15, 30, 45 or 60 mg l^–1) of -naphthaleneacetic acid (NAA) were applied at the equivalent of 100 l ha^–1 to roses grown on an inert substrate in a commercial greenhouse, via repeated foliar sprays at 2, 4, or 8 d intervals over 7 weeks. Unattended or hand-pinched plants were used as negative or positive controls, respectively.The interaction between auxin dose and spray interval had a significant (P ≤ 0.001) influence on the number and growth rate of side-shoots on a stem. All auxin doses tested completely prevented side-shoot development on rose stems at a 2 d spray interval. This high efficacy was attributed to prevention of the irreversible phase-change in the regulation of apical dominance. However, the interaction between auxin dose and spray interval significantly (P ≤ 0.001) influenced the occurrence of leaf epinasty, a physiological condition with a negative impact on cut-shoot quality. Bullheads, another undesirable physiological condition, was significantly (P ≤ 0.001) influenced by auxin dose. This novel technology is expected to lower rose production costs. The data obtained in this study demonstrate the interaction between hormonal and developmental signalling in apical dominance. Possible modes of action are discussed.     

湖南甜瓜瓜绢螟种群动态及杀虫剂田间防治效果评价

为明确湖南甜瓜瓜绢螟[Diaphania indica(Saunders)]的发生规律及筛选控制该害虫的高效药剂,连续3年调查了长沙县钢架大棚内甜瓜瓜绢螟种群数量,并采用田间小区试验评价了6种杀虫剂喷施处理对其防治效果.结果表明,湖南甜瓜瓜绢螟幼虫在5月底至6月初发生,7—10月为发生高峰期.60 g·L-1乙基多杀菌...     

Pre-harvest application of 2, 6-dichloroisonicotinic acid, -aminobutyric acid or benzothiadiazole to control post-harvest storage diseases of melons by inducing systemic acquired resistance (SAR)

Summary

Field-grown rockmelon plants were treated with -aminobutyric acid (BABA), 2,6-dichloroisonicotinic acid (INA), benzothiadiazole (BTH) or water during fruit development and evaluated for increased resistance against plant diseases or post-harvest pathogens. One experiment was conducted at Camden, NSW, Australia (INA, BABA or water). Two experiments were at Griffith, NSW, Australia (INA, BTH or water). Growing plants and harvested fruits were assessed for disease symptoms from natural infections and assayed for the accumulation of chitinase and peroxidase, two major pathogenesis-related (PR) proteins induced as a result of systemic acquired resistance (SAR). Harvested fruit from both BTH- or INA-treated plants showed a significant (P < 0.05) reduction in the severity and incidence of post-harvest storage diseases mainly caused by Fusarium, Alternaria and Rhizopus. However, there were no differences in disease severity and the incidence of rots between using four fortnightly foliar sprays of INA or BTH during flowering and fruit development, or a single spray of BTH, 2 weeks before harvest. Each approach showed an equivalent reduction in storage diseases. Plants treated with BABA showed less resistance against powdery mildew in the field and storage rots from natural inoculum, and lower increases in chitinase and peroxidase activities than those treated with INA. In all trials, an additional post-harvest dip with guazatine [0.05% (w/v)] gave a substantial reduction in melon storage rots. Pre-harvest application of INA or BTH reduced the occurrence of powdery mildew and downy mildew on the leaves. Over the three field-experiments, INA had a small phytotoxic effect causing lesion-like symptoms on leaves and affected plant growth, but not yield, at Camden, when applied during flowering and 2 weeks after flowering. However, INA did not produce any phytotoxic effects in the two experiments at Griffith when applied serially, four times to plants after flowering.