Ag Defense offers protection against cotton aphids
Rijk Zwaan’s Ag Defense line comprises varieties of a number of melon types that have effective natural protection against the cotton aphid Aphis gossypii. This aphid transmits the harmful potyviruses PRSV, WMV and ZYMV. Resistant varieties help growers in their battle against these viruses. Ag Defense is part of Rijk Zwaan’s Defense label.
Interested in Ag Defense varieties?
Vincent van Wolferen
Why growers choose Ag Defense
The Ag Defense varieties offer greater protection against damage from the cotton aphid Aphis gossypii and the viruses spread by these aphids. As a result, melon growers can optimise their integrated pest management. Additionally, Ag Defense contributes to healthier and more sustainably produced plants and fruits since less corrective action is necessary. Fewer cotton aphids mean less honeydew, which in turn improves working conditions.
Benefits of Ag Defense
- Reduced need for crop protection agents
- Healthier crop
- Higher yield
- Better working conditions
Melon types with Ag Defense
Rijk Zwaan offers a wide range of melon types with this resistance. These melon varieties are indicated by the Ag Defense label. Varieties of the following types are available:
- Canteloupe (Harper)
- Piel de Sapo
- Supermarket (Eastern shipper)
- Yellow honey dew
Reduced risk of potyviruses
Although cotton aphids themselves are not particularly harmful to melon plants, they can transmit very harmful viruses, especially the potyviruses PRSV, WMV and ZYMV. These viruses pose a serious threat to crops. The natural resistance against cotton aphids in the Ag Defense varieties reduces the transmission of these viruses.
Damage caused by the cotton aphid Aphis gossypii
All cucurbits are susceptible to potyviruses. The cotton aphid Aphis gossypii is a vector of these viruses. The various types of potyviruses cause similar symptoms.
The cotton aphids feed on the plants and suck out the sap, causing leaves to curl downwards and become distorted. Aphid damage weakens the plants and can have a negative impact on both the quality and quantity of fruits. The honeydew (sugar-rich liquid) excreted by the aphids makes the plants sticky, increasing the likelihood of sooty mould (black mildew) developing on the leaves.
Trials reveal clear differences
Melon varieties with Ag Defense remain healthier than ones without this resistance against the cotton aphid Aphis gossypii. This has been proved both in trials and commercial production in greenhouses and open-field crops with high potyvirus infection levels. The resistant varieties remain healthier, while susceptible varieties in the same greenhouse or field become infected and suffer production problems.
The continued importance of monitoring
The introduction of Ag Defense melon varieties with resistance against cotton aphids offers extra protection. However, it remains important to minimise the risk of infection since some cotton aphids may still be present. Therefore, even after choosing an Ag Defense variety, it is advisable to keep the cotton aphid population down and to monitor the crop for symptoms.