Claudia Daniel

Effects of autumn kaolin and pyrethrin treatments on the spring population of Dysaphis plantaginea in apple orchards.

The impact of treatments with the pyrethrin insecticide Pyrethrum FS and the repellent kaolin product Surround® WP to control the autumn forms of Dysaphis plantaginea Pass. (Hom., Aphididae), a major insect pest of apple, was assessed in 1‐year field experiments in Switzerland. Single and multiple applications of pyrethrin and kaolin were tested at different dates after apple harvesting in autumn 2002 when sexuales of the rosy apple aphid were present. Repeated applications of Surround® WP in autumn significantly reduced the number of females in autumn and, consequently, the number of hatched fundatrices in spring. Single kaolin treatments were less effective. Unexpectedly, neither single nor multiple applications of the contact insecticide Pyrethrum FS had a knock‐down effect on females in autumn. However, pyrethrin significantly reduced the number of hatched fundatrices in spring. Neither pesticide completely controlled the rosy apple aphid but with a more detailed analysis of factors influencing the efficacy of autumn treatments a new approach to control this serious pest could be achieved.

Effects of autumn kaolin treatments on the rosy apple aphid, Dysaphis plantaginea (Pass.) and possible modes of action

Abstract:  Autumn applications of the repellent processed‐kaolin particle film (Surround® WP) might be an alternative to the insecticides commonly used in spring to control the rosy apple aphid, Dysaphis plantaginea (Pass.) (Hom., Aphididae). To assess the mode of action and the impact of kaolin on autumn forms of D. plantaginea, trials were conducted in field cages and in open‐fields in autumn 2003. Choice and no‐choice experiments in field cages showed that winged aphids landed in significantly lower numbers and gave birth to significantly fewer females on kaolin‐treated branches compared with the untreated control. In a first open‐field trial, single applications at 10 different dates and with two different concentrations of kaolin were conducted after harvest to assess the influence of the kaolin concentration on the autumn forms of D. plantaginea. No differences were found between the different concentrations and spraying dates. In a second open‐field trial, single and multiple applications of kaolin were tested at different dates after harvest. Repeated applications of kaolin significantly reduced females in autumn and fundatrices in spring, whereas single kaolin treatments had no significant effect on D. plantaginea. None of the kaolin treatments reduced aphids below the economic threshold. In conclusion, kaolin showed promising results to control autumn forms of D. plantaginea. However, with a more detailed forecasting model for the autumnal flight of this aphid, treatments could be conducted more precisely and more effectively, especially in years with exceptional climatic conditions, such as in 2003.

Processed kaolin as an alternative insecticide against the European pear sucker, Cacopsylla pyri (L.)

Abstract:  Application of processed kaolin particle film (Surround® WP; Engelhard Corporation, Iselin, NJ, USA) repels insects without lethal effects; hence side effects on beneficial arthropods are low. Processed kaolin may be an alternative to broad‐spectrum insecticides used against European pear sucker, Cacopsylla pyri (L.), in organic and conventional pear production. A small‐plot field trial was conducted in spring 2003 to assess this hypothesis. Multiple applications of processed kaolin during the first flying period of C. pyri significantly reduced the number of nymphs compared to the untreated control. Processed kaolin protected pear trees at least as good as the standard organic insecticide rotenone. Since the effects on the summer population could not be assessed in this small‐plot trial due to the high mobility of the adult C. pyri, a large‐plot trial was conducted in 2004. Thereby, the processed kaolin showed a very high efficacy and the population of C. pyri was kept under a damaging level over the whole season. At the end of June the population density of C. pyri in the processed kaolin treated area was lower than in the IPM treated plot. In conclusion, kaolin shows promise as an alternative control for C. pyri in organic and IPM orchards.

Field applications of Beauveria bassiana to control the European cherry fruit fly Rhagoletis cerasi

Field experiments with foliar applications of Beauveria bassiana ATCC 74040 (product Naturalis‐L) were conducted to control the European cherry fruit fly Rhagoletis cerasi Loew (Diptera: Tephritidae), a major pest of cherries in Europe. Naturalis‐L was applied at concentrations of 250 ml per 100 l in 7‐day intervals during the flight period of R. cerasi. Flight activity monitored by yellow sticky traps was only slightly affected by treatments. Infection and mycosis of adult cherry fruit flies was shown to be possible under field conditions. Fruit infestation was assessed at harvest. The number of infested fruits was significantly reduced by 65% with foliar applications of Naturalis‐L. These results were obtained from five experiments in 2 years with considerably different weather conditions (wet vs. dry) and in different orchards with different flight intensities of R. cerasi (low vs. high) and different cherry varieties (early ripening vs. late ripening). In conclusion, the application of Naturalis‐L is a suitable and economically feasible strategy for controlling R. cerasi in organic cherry production. The product Naturalis‐L is currently registered for cherry fruit fly control in Italy and Switzerland.

A New Visual Trap for Rhagoletis cerasi (L.) (Diptera: Tephritidae)

The European cherry fruit fly, Rhagoletis cerasi (L.) (Diptera: Tephritidae), is the most important pest of sweet cherries in Europe. The aim of our experiments was to develop a new, cost-efficient, lead chromate-free and more eco-friendly trap for monitoring and mass trapping of R. cerasi. Five different-colored yellow panels and three different trap shapes were compared to a standard Rebell® amarillo trap in three experimental orchards in 2012. Trap color F, with a strong increase in reflectance at 500–550 nm and a secondary peak in the UV-region at 300–400 nm, captured significantly more flies than the standard Rebell® amarillo trap. Yellow traps with increased reflectance in the blue region (400–500 nm) were least attractive. Trap shape was of minor importance, as long as the object was three-dimensional and visible from all directions. Based on economic and practical considerations, a cylinder-shaped trap “UFA-Samen Kirschenfliegenfalle” was developed for commercial use and is currently under on-farm evaluation.

Rhagoletis cerasi: Oviposition Reduction Effects of Oil Products

The European cherry fruit fly, Rhagoletis cerasi (L.) (Diptera: Tephritidae), is a highly destructive pest. Methods to control it are limited and alternatives are needed. Observations of cherry fruit flies suggest that females exert much effort to penetrate cherries at color change stage (from green to yellow) for oviposition. Therefore, the question arose as to whether a physical barrier on the fruit surface could reduce oviposition. The effects of different commercial horticultural oil products on R. cerasi oviposition were evaluated in a series of laboratory, semi-field and field experiments. In the laboratory experiments, the rate of successful oviposition on fruits treated with 0.25% v/v of the rapeseed oil product Telmion was significantly reduced by 90% compared to the untreated control. In semi-field experiments, deposits of 1% of rapeseed, mineral and paraffinic oil significantly reduced oviposition for up to 3 days. Semi-field experiments indicated that the oil products lose efficacy within 3 to 6 days after application due to degradation. Although treatments with the rapeseed oil product Telmion reduced infestation rates in an on-farm field experiment, the infested fruit clearly exceeded the level of market tolerance of 2%. Further research is needed to assess whether combinations of oil products, higher application rates and different formulations might improve field efficacy.

Effect of cultural methods on leaf spot (Mycosphaerella fragariae) and gray mold (Botrytis cinerea) damage in strawberries

Damage of leaf spot, caused by Mycosphaerella fragariae and gray mold also called Botrytis fruit rot, caused by Botrytis cinerea, average fruit weight and yield were evaluated with regard to cultural methods over 2years. Leaf spot damage decreased significantly by around 90% due to leaf sanitation (removal of dead and leaf spot infected leaves in early spring) and by 50% due to plantation in a one-row-system instead of a two-row-system. When all leaves including the healthy green ones were removed in early spring, average fruit weight decreased significantly by 10%. Fruit sanitation – the third treatment – did not influence any of the measured parameters. Neither leaf sanitation nor fruit sanitation (removal of damaged fruits during harvest) reduced B. cinerea damage significant. Only the combination of a one-row-system, leaf sanitation and fruit sanitation almost halved (not significantly) B. cinerea damage in the first crop year compared to a two-row-system without leaf and fruit sanitation. B. cinerea damage correlated significantly and positively with the biomass of plants by R2= 0.47. According to this study and the cited literature it is suggested for humid Central European conditions to apply a one-row-system combined with leaf sanitation in early spring and fruit sanitation during harvest if fruit density is high, to reduce the risk of damages in larger dimension caused by M. fragariae and B. cinerea.

Screening of 25 different natural crop protection products against Drosophila suzukii

Drosophila suzukii is a major pest of soft‐skinned fruits, and insecticides are often used to prevent fruit damage caused by oviposition. As D. suzukii produces many generations per year, repeated insecticide applications are required. Furthermore, D. suzukii attacks ripening and ripe fruits shortly before harvest. Therefore, the use of synthetic insecticides is limited by long pre‐harvest intervals and maximum residue limits. To be able to offer producers immediate and sustainable solutions, we tested 25 natural crop protection products with three different application methods in a laboratory screening. We show that application method is an important factor for the efficacy of the tested products. Of six natural insecticides, only Spinosad was toxic for D. suzukii and reduced the oviposition on treated blueberries. The tested oil products had no control effect and products based on different entomopathogenic fungi and Bacillus thuringiensis rather enhanced oviposition. Mineral products (Kaolin, CaCO3, Ca(OH)2 and clinoptilolith) applied as spray solutions were not toxic, but significantly reduced oviposition on blueberries. We provide the first study in which different application methods have been used to compare numerous, commercially available, natural crop protection products with different modes of action against adult D. suzukii. Our findings provide consultants and producers with important insights for the development of sustainable pest control strategies against D. suzukii.

The Distance Between Forests and Crops Affects the Abundance of Drosophila suzukii During Fruit Ripening, But Not During Harvest

Abstract Drosophila suzukii (Matsumura; Diptera: Drosophilidae) is an invasive pest with the ability to reproduce not only in various soft fruit crops, but also in numerous wild hosts. Forests and forest edges harbor many wild hosts, provide suitable microclimatic conditions and are therefore thought to enhance the abundance of D. suzukii. Although the comprehension of pest activity based on specific landscape elements is important to implement efficient management strategies, knowledge of how forests affect the abundance of D. suzukii in nearby crops is very limited. We conducted a monitoring study with liquid baited traps across different crops at different distance from the forests. During fruit ripening, more flies were captured in crops closer to forests (22.21 % decrease per 500 m distance), whereas there was no significant relationship during harvest. Since color can affect the efficiency of D. suzukii traps, we have used traps either with a red or black lid. Acquired data suggest that traps with black lids capture significantly more flies than traps with red lids. We provide a quantitative estimation of how and when distance from adjacent forests affects the abundance of D. suzukii in crop fields. Our results can help consultants and farmers to estimate the pest pressure of D. suzukii in crop fields near forested, noncrop areas and to implement appropriate control strategies when D. suzukii populations increase and fruit becomes susceptible to infestation.

Reduced crop damage by self-regulation of aphids in an ecologically enriched, insecticide-free apple orchard

Enhancing natural enemies for pest management in agriculture is an expanding approach offering new opportunities for pest control and the potential to reduce insecticide use. Numerous studies in a variety of cropping systems clearly have shown that adequate measures can benefit natural enemies. However, although carry-over effects from an increase in natural enemies and a subsequent decrease in pest populations leading to a reduction in crop damage are always assumed, they are rarely proven. We established an insecticide-free apple orchard optimized for the self-regulation of pests by supporting natural enemies with shelter, nectar, alternative prey/hosts, and pollen. For six growing seasons, we focused on the control of the major apple pest Dysaphis plantaginea. While fruit damage after the second fruit drop was not affected by aphidophagous insect guilds, it was negatively related to spider abundance in the previous autumn, when aphids immigrate back to the orchard to establish the next generation. In detail, we found that an increase in spider web area reduced the number of aphid fundatrices in spring and subsequently fruit damage. Our findings indicate the rarely proven carry-over effect of enhanced natural enemies on decreased crop damage and we show for the first time, how the rosy apple aphid can be managed without the use of insecticides.