The forecasted 9.1 billion population in 2050 will require an increase in food production for an additional two billion people. There is thus an active debate on new farming practices that could produce more food in a sustainable way. Here, we list agroecological cropping practices in temperate areas. We classify practices according to efficiency, substitution, and redesign. We analyse their advantages and drawbacks with emphasis on diversification. We evaluate the potential use of the practices for future agriculture. Our major findings are: (1) we distinguish 15 categories of agroecological practices (7 practices involve increasing efficiency or substitution, and 8 practices need a redesign often based on diversification). (2) The following agroecological practices are so far poorly integrated in actual agriculture: biofertilisers; natural pesticides; crop choice and rotations; intercropping and relay intercropping; agroforestry with timber, fruit, or nut trees; allelopathic plants; direct seeding into living cover crops or mulch; and integration of semi-natural landscape elements at field and farm or their management at landscape scale. These agroecological practices have only a moderate potential to be broadly implemented in the next decade. (3) By contrast, the following practices are already well integrated: organic fertilisation, split fertilisation, reduced tillage, drip irrigation, biological pest control, and cultivar choice.

/pdf/agroecological-practices-for-sustainable-agriculture-a-5g4te0f8oo.pdf

Agroecological practices for sustainable agriculture. A review

Farmers are facing serious plant protection issues and phytosanitary risks, in particular in the tropics. Such issues are food insecurity, lower income in traditional low- input agroecosystems, adverse effects of pesticide use on human health and on the environment in intensive systems and export restrictions due to strict regulations on quarantine pests and limits on pesticide residues. To provide more and better food to populations in both the southern and northern hemispheres in a sustainable manner, there is a need for a drastic reduction in pesticide use while keeping crop pest and disease damage under control. This can be achieved by breaking with industrial agriculture and using an agro- ecological approach, whose main pillar is the conserva- tion or introduction of plant diversity in agroecosystems. Earlier literature suggest that increasing vegetational biodiversity in agroecosystems can reduce the impact of pests and diseases by the following mechanisms: (1) resource dilution and stimulo-deterrent diversion, (2)

https://link.springer.com/content/pdf/10.1007%2Fs13593-011-0022-4.pdf

Plant species diversity for sustainable management of crop pests and diseases in agroecosystems: a review

Potato crop is the fourth main food crop in the world and it will certainly feed a big part of the global population in the next years. The economical outlets for this crop are great; however, numerous diseases either soil- or air-borne can cause huge losses in the production. Worldwide, about 40 soil-borne diseases affect potato and cause severe damages especially on tubers, the economically most important part of the plant. The occurrence and development of soil-borne diseases depend on very diverse factors affecting either the pathogen or the plant. Favorable conditions for potato diseases development are frequently the same as the conditions needed for potato growth: temperature between 10°C and 25°C, high humidity, medium pH, etc. Adapted cultural practices such as a rotation longer than 4 years, appropriate fertilization and water management, an adapted delay between haulm killing and harvest, and dry and cool conditions for tuber storage are good ways to control potato diseases. In most cases, potato pathogens develop specific survival forms, dissemination ways and host penetration methods. The genetic variability of the pathogens implies the use of adapted diagnostic and control methods. Decision support systems developed to predict yield losses allow choosing good control methods such as the use of healthy seeds, adapted pesticides, cultural practices, and biological control agents for each potato disease. The complexity of the interactions between a pathogen and its host, influenced by biotic and abiotic factors of the environment, make the control of the diseases often very difficult. However, deep knowledge of pathosystems allows setting up integrated pest management systems allowing the production of healthy and good quality potatoes.

/pdf/potato-soil-borne-diseases-a-review-cb2rrubef2.pdf

Potato soil-borne diseases. A review

Plant-parasitic nematode management via biofumigation using brassica and non-brassica plants: Current status and future prospects

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Summary

Ninety accessions of non-tuber bearing Solanaceae were screened for (i) resistance to and (ii) stimulatory effect on juvenile hatch of potato cyst nematodes, and (iii) their growth under temperate climatic conditions. All plant species belonging to the genus Solanum tested induced hatching but this effect was most pronounced for plant species of the Solanum nigrum complex. Hatching of juveniles was hardly or not stimulated by other plant genera of the Solanaceae. Solanum sisymbriifolium combined a high hatching effect with complete resistance to both Globodera rosiochiensis and G pallida. Two S. nigrum varieties showed full resistance to G rostochiensis and a high level of resistance to G pallida. Moreover, S. sisymbriifolium and the two varieties of S. nigrum performed very well under Dutch field conditions and, therefore, they are suggested as candidate trap crops for the control of potato cyst nematodes.

Screening of non-tuber bearing Solanaceae for resistance to and induction of juvenile hatch of potato cyst nematodes and their potential for trap cropping

Summary
In 1997 and 1998 the stimulation of hatch of potato cyst nematodes (PCN) by a trap crop was studied at various times during the growing season in a container and a field experiment. Solanum nigrum‘90-4750-188’was used as the trap crop in both experiments and was sown on 1 May, 16 June or 1 August in two successive years on different plots. Neither experiment revealed much seasonal variation in hatchability of PCN juveniles under a trap crop. In the container experiment, the hatch of the Globodera pallida Pa3 population was equally and strongly stimulated (89%) at all sowing dates in both years, except for the 1 August sowing in 1998 (when the hatch was 77% under extremely wet soil conditions). In the control treatment with non-hosts (flax followed by barley) the total spontaneous hatch was 50% over 2 yr. In the field experiment, the hatch of PCN, averaged over the four populations, was also equally stimulated (71%) at all sowing dates in both years. In the control treatment with non-hosts (flax-barley) the total spontaneous hatch was 36% over 2 yr. Total hatch under the trap crop over 2 yr varied between the four PCN populations from 63% to 80%.

In 1998 and 1999, control of potato cyst nematodes (PCN) by the potential trap crops Solanum sisymbriifolium and S. nigrum‘90-4750-188’was studied in the field. Potato was also included as a trap crop. In the 1998 experiment, potato, S. sisymbriifolium and S. nigrum strongly stimulated the hatch of PCN compared with the non-host white mustard (Sinapis alba). Roots of potato and white mustard were mainly found in the top 10 cm of soil, whereas roots of S. sisymbriifolium and S. nigrum were also abundant at depths of 10–20 cm and 20–30 cm. In the 1999 experiment, soil infestation with PCN decreased markedly with potato and S. sisymbriifolium as trap crops. In plots moderately to severely infested with 2-yr old cysts (2–29 juveniles ml−1 air dried soil), potato reduced soil infestation by 87% and S. sisymbriifolium by 77%. In plots moderately to severely infested with 1-yr old cysts the reductions were 74% and 60%, respectively. The reduction was least on plots very severely infested with PCN (110–242 juveniles ml−1 soil): 69% and 52% for potato and S. sisymbriifolium, respectively. Soil infestations of plots that were initially slightly to severely infested with the root-knot nematode Meloidogyne hapla were greatly reduced under fallow and S. sisymbriifolium but increased under potato. From these and previous experiments it was concluded that, for several reasons, S. sisymbriifolium is a promising trap crop.

Effects of potential trap crops and planting date on soil infestation with potato cyst nematodes and root-knot nematodes

Growth and development of three plant accessions with potential for use as trap crops for potato cyst nematodes (PCN), Solanum sisymbriifolium and two varieties of S. nigrum, were studied under 12 h and 17 h photoperiods. In pot experiments, rate of plant emergence, plant height, and shoot and root mass were greater for the S. nigrum varieties ‘90-4750-188’ and ‘88-4750-061’ than for S. sisymbriifolium and markedly greater than for a S. nigrum variety found as a weed of arable fields in The Netherlands. However, the last mentioned S. nigrum variety produced the most berries. Plant height and shoot weight of all the S. nigrum varieties were greater under the longer photoperiod, whereas the root mass was hardly affected. Plant height and shoot weight of S. sisymbriifolium also were greater under the longer photoperiod but the root weight was less. Under field conditions, with sowing dates from the end of March to mid August, S. sisymbriifolium and S. nigrum ‘90-4750-188’ grew better than S. nigrum ‘88-4750-061’. In contrast to S. nigrum, S. sisymbriifolium appeared resistant to night frosts in autumn. The stubbles of both S. sisymbriifolium and S. nigrum showed good regrowth after cutting the plants 5 or 10 cm above the soil surface 11 wk after sowing. In a pot experiment, all the plant accessions strongly reduced the numbers of juveniles in cysts compared with flax. Tolerance to Globodera rostochiensis of S. sisymbriifolium and S. nigrum‘90-4750-188’ was investigated in pot experiments under glasshouse conditions in sandy soil at pH 4.8 and 6.0. At soil infestation levels ranging from 0 to 56 juveniles ml−1 soil, S. sisymbriifolium appeared much more tolerant than S. nigrum ‘90-4750-188’. Shoot yield of S. nigrum decreased markedly with increasing soil infestation and root weight also decreased, except at pH 4.8 and light infestation levels. Both S. sisymbriifolium and S. nigrum grew better at soil pH 4.8 than 6.0. The proportion of lateral roots in the total root mass increased in both species with increasing PCN infestation and soil pH. However, although the proportion of lateral roots in plants grown at soil pH 6.0 was greater at PCN infestations up to 14 juveniles ml−1 soil, the proportion of laterals in S. nigrum was considerably less at PCN infestations of 56 juveniles ml−1 soil. The proportion of PCN juveniles hatching was similar for the two species and decreased slightly with increasing initial nematode population densities.

Growth and development of plants with potential for use as trap crops for potato cyst nematodes and their effects on the numbers of juveniles in cysts

A field experiment in which main-crop potatoes were grown every other year was conducted on a sandy soil from 1994 to 1999. The aim of the experiment was to control soil-borne pathogens of potato with ecologically sound methods. Potato grown as a trap crop from the end of April to the end of June (8 wk) was used to control potato cyst nematodes (PCN) (Globodera pallida), and its effects on other important soil pathogens and on the growth of a subsequent potato crop were also assessed. Additional experimental treatments were a potato crop from which the haulm was removed and a green manure crop. Three potato cultivars with different degrees of resistance to PCN were grown as the main crop. Duplicate sets of the experiment were run concurrently. The PCN were effectively controlled by the potato trap crop. When a highly resistant potato cultivar was grown as a main crop after the trap crop, the post-harvest soil infestation was very low. When a moderately resistant cultivar was grown after the trap crop the soil infestation also remained low. When the trap crop was alternated with a susceptible potato cultivar as a main crop, soil infestation increased slightly, but the degree of control when compared with no trap crop averaged 96%. Soil infestation with root-knot nematodes (mainly Meloidogyne hapla) increased when potato was grown as a trap crop, but soil infestation with the root-lesion nematode Pratylenchus crenatus was not affected. Stem canker caused by Rhizoctonia solani was not affected by the trap crop but black scurf (sclerotia of R. solani) on tubers was reduced. Soil infestation with Verticillium dahliae declined in one of the duplicate sets of the experiment but not in the other. However, stem infections by V. dahliae were significantly decreased in both sets, although the effect depended on the PCN-resistance level of the potato cultivar. When a highly resistant potato cultivar was grown Verticillium stem infections were not significantly affected, they were decreased with a moderately resistant cultivar but the decrease was most pronounced with a PCN-susceptible cultivar. Senescence of a following potato crop was not influenced by the trap crop when a highly PCN- resistant cultivar was grown, but it was delayed in the case of a moderately resistant or a susceptible cultivar, resulting in higher tuber yields for those cultivars. The experiment proved that a trap crop can be an alternative to chemical soil disinfection but, for several reasons, the potato itself is not an ideal crop for this purpose; a trap crop other than potato must be developed.

K. Scholte

Papers

Screening of non-tuber bearing Solanaceae for resistance to and induction of juvenile hatch of potato cyst nematodes and their potential for trap cropping

Effects of potential trap crops and planting date on soil infestation with potato cyst nematodes and root-knot nematodes

Growth and development of plants with potential for use as trap crops for potato cyst nematodes and their effects on the numbers of juveniles in cysts

Effect of potato used as a trap crop on potato cyst nematodes and other soil pathogens and on the growth of a subsequent main potato crop