Nobody likes wormy apples and, according to the supermarkets at least, blemished apples and pears simply do not sell, which means some of our favourite fruits are subject to significant doses of pesticides.
ENDURE’s pomefruit (apples and pears) case study team aims to demonstrate the effectiveness and feasibility of using preventive or protective integrated control strategies and, as the first step in achieving this, has conducted a broad survey of European research projects relating to integrated control strategies.
The team, part of ENDURE’s Research Activity 1, comprised of groups conducting case studies on a range of important crops, note that integrated pomefruit production is well-established across most European countries, though not all producers have adopted integrated pest management (IPM).
However, they say, apple scab (Venturia inaequalis ), brown spot of pears (Stemphylium vesicarium ) and codling moth (Cydia pomonella ) are still responsible for large-scale chemical crop protection and residues on fruits, which damages their healthy image.
The team found that 23 European institutes (eight of them part of the ENDURE Network of Excellence) are conducting research on apple scab, with an identical number (10 from ENDURE) tackling codling moths. They identified nine institutes (two from ENDURE) conducting research on brown spot of pear. The latter is remarkable for a disease that appeared so recently, they say, and may reflect the damage caused by the disease and the difficulty of controlling it with standard fungicides.
The team further analysed each project to see what it was focussing upon. They discovered that a substantial number were concerned with background and more fundamental knowledge for the development of future integrated control strategies, no surprise for a relatively new disease such as brown spot on pear, but somewhat unexpected for well-studied problems such as apple scab and codling moth.
They found many projects concerned the development of warning systems or decision support systems. “This shows a very practical approach to reducing the environmental impact of pesticides while at the same time adequately controlling the diseases or pests,” the authors note.
They conclude that there is a sound basis for the further development of integrated control strategies in Europe and good contacts with extension services (farmers’ advisory services) which can help to implement both existing and future strategies. However, they note that more contacts with new European Union countries (such as Poland, Bulgaria, Slovenia and the Baltic States) are needed to further implement integrated control strategies in these parts of Europe.
More about the pests
Apple scab is a major disease of apples caused by the fungus Venturia inaequalis . Infections can develop on both fruit and leaves. On fruit it causes lesions on the skin and infections occurring close to harvest may only become apparent as dark, sunken spots on fruit in storage. Infection begins in the spring when suitable temperatures and moisture promote the release of spores which are carried by the wind into trees. Non-chemical controls can include the removal of leaf litter, the pruning of infected shoots and choosing cultivars that are resistant or partially resistant to scab, though these may not be commercially desirable. Chemical control includes regular spraying with fungicides or, traditionally, spraying with copper or Bordeaux mixture. Although unsightly, scab affects only the skin of the fruit and it remains edible, though difficult to sell.
The codling moth (Cydia pomonella ) is native to Europe but has spread far afield, including North America. Their larvae are the common apple worm or maggot and can also attack pears, walnuts and other tree fruits. Adult codling moths emerge in late spring and the females lay eggs on or near developing fruits. After hatching, the caterpillar bores into the fruit and feeds in the core region. Infestations are often managed by the application of pesticides and the timing of these has been made more accurate using pheromone traps, which allow producers to trap male moths and calculate the best time to spray. Other more environmentally benign measures are also available, including mating disruption, which uses devices typically made of rubber or plastic to release female pheromones and physical measures such as trunk banding, in which corrugated cardboard is wrapped around the trunk and intercepts larvae. The most widely used microbial control employs granulosis virus, which is eaten by larvae and kills them. It is a tactic that has been tested extensively in Europe and elsewhere. Other strategies include the 'attract and kill' system, which uses sex pheromones to attract male codling moths and fast-acting insecticide to kill them. Nematodes (roundworms) have also been used to target over-wintering pupae.
Brown spot of pear (BSP) is a fungal disease caused by Stemphylium vesicarium (which also causes problems for crops such as garlic, onion and asparagus) and is a relatively new problem for pear producers having been first reported in Italy in the 1970s and Spain a decade later. Though it remains a particular problem in southern Europe, it has also been reported in France, Portugal, The Netherlands and Belgium. Epidemics can be severe and cause heavy crop losses for growers. The standard chemical solution is to spray regularly with fungicides, however this can lead to environmental problems, leaves residues on the fruit and there is some evidence of fungicide resistance developing. The spread of the disease is susceptible to temperature and humidity variations, so forecasting models can help to better time sprays. However, the problem is not helped by the fact that some of the most commercially successful cultivars, such as Conference, are particularly susceptible to BSP.
Last update: 24/05/2023 - ENDURE © 2009 - Contact ENDURE - Disclaimer