Tomato leafminer – Tuta absoluta Meyrick (Lepidoptera,Gelechiidae) – current status in Montenegro

Tomato leafminer Tuta absoluta was detected for the first time in Montenegro using pheromone traps in the middle of July 2010, in greenhouses in one location at the Montenegrin sea coast. In the period from the end of July to the first week of August, moths were captured in pheromone traps from other locations along the sea coast and surroundings of the city of Podgorica. According to the survey carried out by the authors from July to September 2010, T. absoluta was present in greenhouses in all tomato‐producing areas, while outdoors it was found only in the coastal area. Monitoring of T. absoluta continued in 2011. Pheromone traps were set up in five locations in the main tomato‐producing areas, both in greenhouses and outdoors, between 4 and 15 May. The first captured moths were detected after 7–15 days in all inspected locations, and captures continued until the end of September. According to the number of captured moths and the damage observed, it can be concluded that the population level in 2011 was lower in comparison with 2010, when up to 100% losses were detected in tomato crops in several locations. In 2011, tomato producers were already being informed about the pest and means of control, so most of them applied cultural and chemical control measures.     

‘Universal’ spray droplet adhesion model – accounting for hairy leaves

The adhesion of a spray droplet upon initial contact with a leaf surface is extremely important to spray efficacy and is dependent on dynamic interactions between droplets (formulation, size, velocity) and leaf (micro‐topography, surface chemistry, veininess, hairiness and orientation). A ‘universal’ spray droplet adhesion model has previously been developed, using 50% aqueous acetone contact angles as a measure of leaf surface properties; this model satisfactorily predicts initial adhesion over a range of formulation surface tensions, droplet sizes and velocities. However, it failed to fit data from hairier leaves. This study investigates initial spray droplet adhesion on hairy leaves. Two categories of hairy leaves were identified by how the droplets penetrate the leaf hairs, Wenzel (hairy) and Cassie–Baxter (super hairy). For the Wenzel‐type, a simple constant accounted for the increased droplet shatter caused by the hairs. For the Cassie–Baxter‐type, a cushioning factor was introduced to account for the absorption of kinetic energy at impact by the hair mat. The cushioning factor was estimated by measuring the relative height of the hair mat. By including these two parameters, the new model successfully predicted the mean adhesion of non‐hairy, hairy and super‐hairy plants (R² = 0.96). This model and the underlying principles determining hairy leaf adhesion developed in this article will help develop spray formulations effective at targeting hairy‐leaved weed and crop species.     

Herbicides – a two‐edged sword*

Summary Weeds cause yield losses and reductions in crop quality. Prior to the introduction of selective herbicides, the drudgery of manual weeding forced farmers to adhere to a suit of weed management tactics by carefully combining crop rotation, appropriate tillage and fallow systems. The introduction of selective herbicides in the late 1940s and the constant flow of new herbicides in the succeeding decades provided farmers with a new tool, ‘the chemical hoe’, putting them in a position to consider weed control more independently of the crop production system than hitherto. The reliance on herbicides for weed control, however, resulted in shifts in the weed flora and the selection of herbicide‐resistant biotypes. In the 1980s, the public concern about side‐effects of herbicides on the environment and human health resulted in increasingly strict registration requirements and, in some countries, political initiatives to reduce the use of pesticides were launched. Today, the number of new herbicides being introduced has decreased significantly and integrated weed management has become the guiding concept. Farmers also have the option of growing herbicide‐resistant crops where the biology of the crop has been adapted to tolerate herbicides considered safe to humans and environmentally benign. This paper discusses some of the recent developments in herbicide discovery, technology and fate, and sketches important future developments.     

Pesticidal natural products – status and future potential

There is a long history of using natural products as the basis for creating new pesticides but there is still a relatively low percentage of naturally derived pesticides relative to the number of pharmaceuticals derived from natural sources. Biopesticides as defined and regulated by the US Environmental Protection Agency (EPA) have been around for 70 years, starting with Bacillus thuringiensis, but they are experiencing rapid growth as the products have got better and more science‐based, and there are more restrictions on synthetic chemical pesticides. As such, biopesticides are still a small percentage (approximately US$3–4 billion) of the US$61.3 billion pesticide market. The growth of biopesticides is projected to outpace that of chemical pesticides, with compounded annual growth rates of between 10% and 20%. When integrated into crop production and pest management programs, biopesticides offer the potential for higher crop yields and quality than chemical‐only programs. Added benefits include reduction or elimination of chemical residues, therefore easing export, enabling delay in the development of resistance by pests and pathogens to chemicals and shorter field re‐entry, biodegradability and production using agricultural raw materials versus fossil fuels, and low risk to non‐target organisms, including pollinators. Challenges to the adoption of biopesticides include lack of awareness and education in how to deploy their unique modes of action in integrated programs, testing products alone versus in integrated programs, and lingering perceptions of cost and efficacy. © 2019 Society of Chemical Industry     

Late Blight Forecasting in Norway 1957–19801

A regular late-blight warning service was established in Norway in 1957, run by the Plant Protection Service. The service was revised in 1965 and from that year the warnings were distributed by the Norwegian Institute of Meteorology. The criteria for warnings are described. A regression analysis of the relationship between warnings and intensity of late-blight epidemics in 1957–1980 showed no significant differences between locations, but significant differences in the relationship between years and periods. The weather in the years 1973 to 1978 caused unfavourable conditions for late blight in all parts of the country. In 1979 and 1980 the weather changed and favourable climate to late blight occurred in most regions of the country, but the progress of epidemics in 1979 was slower than expected due to reduced inoculum potential. In 1980 a more normal progress of epidemics was observed, which indicated a reestablishment of the inoculum potential in the autumn of 1979.     

Synchytrium endobioticum – risk from biogas plants?

Synchytrium endobioticum is one of the most important pathogens of potato and is known for its persistent propagation structures. Under favourable conditions, infection of highly susceptible potato cultivars leads to clearly visible cauliflower‐like tissue warts, the typical symptom of potato wart disease. However, unfavourable infection conditions or low infection pressure may result in symptoms being overlooked. Thus, the introduction of pathogen structures into stages of the processing industry cannot be ruled out. As the amounts of processed potato products continue to rise, phytosanitary risks from processing discarded potatoes and potato waste in biogas plants have to be considered. Hence, the resilience of resting spores against mesophilic anaerobic digestion was analysed in stirred tank reactors. Laboratory‐scale results show that S. endobioticum not only withstands mesophilic anaerobic digestion but also subsequent storage of the digestate for at least 4 weeks. Large numbers of viable resting spores were detectable by microscopic assessment in all samples. Viability was proved and verified additionally by bioassay. Consequently, potatoes, potato waste and processing water from potato processing industries used in biogas plants pose a phytosanitary risk if the accruing digestates are returned as fertilizer to arable land.     

Global internet trade of plants – legality and risks

Internet trade of plants has been investigated in a short study that focused on plants for planting imported into Germany from third countries worldwide. Internet trade of plants may pose a high phytosanitary risk when commodities are infested with non‐native pests including quarantine pests. The offers of 1097 internet traders, in particular non‐European traders, have been checked. One hundred and seventeen consignments of plants were purchased from 70 different internet traders and investigated in detail. As only individual plants were purchased the study shows in particular what is available for purchase to private consumers. The study revealed that 89% of the consignments did not comply with phytosanitary import requirements for one or more reasons. In all these cases the phytosanitary certificate was missing and in 68% of the consignments the customs declaration was missing or wrong. Wrong customs declarations indicate that these internet traders ignored the import requirements or provided incorrect information to the import authorities. Prohibited plants could be easily bought via the internet. In addition, harmful organisms were found in 13% of the consignments and 2% of these were quarantine pests. All consignments that were accompanied by the required phytosanitary certificate issued by the National Plant Protection Organisation of the exporting country (11%) complied with the EU and German, respectively, import requirements.