Asteraceae

Aphid damage on Asteraceae

Asteraceae for large-scale production (sunflower)

On sunflower, the damage wreaked by the leafcurl plum aphid (Brachycaudus helichrysi) is often spectacular. The presence of colonies brings crinkling of foliage). This effect is at its worst the earlier the outbreaks occur, at the 2-3 leaf-pair stages or even sooner. The yield loss can reach 4 q (400kg)/ha. The crinkling can create favourable sites for germination spores of Sclerotinia, white mould. In case of an aphid attack, an insecticide application can be justified. The products authorized for foliar treatment are effective. Spraying must be done early on, at the beginning or just before the phase of exponential population increase. The aphid colonizations occurring after floral bud release has been achieved are no longer a threat

The sunflower attracts a great many insects searching for pollen, nectar or exudates, particularly bees. The anti-aphid treatments must therefore be accomplished outside the pollen-gathering periods, preferably in the evening. All the approved products carry the message “harmless for bees”.

Asteraceae for market-garden crops (lettuce, chicory, endive, artichoke, salsify)

Several aphids attack leaves of lettuce and green salad produce: the green peach aphid (Myzus persicae), the lettuce aphid (Nasonovia ribisnigri), and the sowthistle aphid (Hyperomyzus lactucae). These species, present throughout the cropping time, are more harmful in nurseries and at the beginning of cultivation. The lettuce root aphid (Pemphigus bursarius) and the large lettuce root aphid (Protrama flavescens) attack the roots. They produce dense colonies, greyish and covered with a white powdery substance. These colonies are located on the collar of plants and dispersion is possible throughout the root system. Alates of Pemphigus bursarius colonize the lettuce crops from June. Many other species of aphid belonging to the genus Trama live on lettuce roots or collar. They are usually difficult to identify. Among the viral diseases affecting salad produce (lettuce, chicory, endive), the lettuce mosaic virus (LMV) is the most widespread. It is disseminated by numerous species of aphid including the green peach aphid (Myzus persicae). On young plants, it induces a faded marbling effect, an asymmetrical blade with acute irregular serrations; a later attack induces a green colour with deformed leaves, a frail plant which does not firm up. A mixed control approach against the leaf aphids of lettuce makes weekly inspection necessary. The threshold for an aphicide operation is 10-20% of lettuce plants hosting a colony of aphids.

The aphids are the most prominent pests of artichoke crops, particularly those which attack the inflorescence because they can severely jeopardize the value of the harvest. The black bean aphid (Aphis fabae) very rapidly deforms the colonized leaves and leads to the development of sooty mould. The green plum / leafcurl plum aphid (Brachycaudus helichrysi) is installed between bracts which redden and harden. The green artichoke-globe artichoke aphid (Capitophorus horni) and the thistle aphid (Brachycaudus cardui) are located on the lower side of the leaves but do not induce any leaf deformation. Any aphicide control technique must be performed early and strongly in order to obtain a healthy crop already before launching the harvest which, owing to the time it takes, makes the last treatment operations difficult to plan. The viral diseases currently present no serious problems for artichoke cultivation.

On salsify, the threat of damage comes from the black bean aphid (Aphis fabae), on foliage, and the root aphids (Trama spp., Protrama flavescens), which gather on the collar and upper parts of roots. The presence of the latter aphids is revealed by the whitish waxy substance certain species cover themselves with. Their colonies proliferate in June on young roots. Infestations can also occur at the end of the season but they are not so serious. Controlling the root aphids is difficult. Well conducted watering operations can help contain them as dry conditions encourage their proliferation.

A control strategy against artichoke aphids has been developed in Brittany 

A control programme run over several years led to an overall fall in artichoke aphid populations:

  • at the end of winter and the beginning of spring, such control is only envisaged at a threshold of 10 green aphids per leaf or if the black aphid is present
  • from spring to the beginning of autumn,  the integrated approach is adopted by applying the treatment threshold criterion and selection of insectides that spare the auxiliary fauna (ladybirds, chrysopes and so on)
  • at the end of autumn, control consists in avoiding the expansion of foci during winter

Modification date : 07 February 2023 | Publication date : 09 July 2014 | Redactor : Maurice Hullé, Evelyne Turpeau, Yvon Robert, Yves Monnet, Charles-Antoine Dedryver