Agrilus mali attacks several species of Malus (Rosaceae – including cultivated apple M. domestica, as well as the wild apple M. sieversii). Several Rosaceae species in the genera Prunus, Sorbus, Cydonia, and Pyrus are unconfirmed hosts. Agrilus mali infests mainly branches as well as the trunks of young trees (with thin bark).

The likelihood of entry into Kazakhstan through natural spread is considered very high (low uncertainty), because of the very close proximity and continuous presence of M. sieversii between places in northern Xinjiang (Yili Valley, China), where A. mali is present, and Kazakhstan. For the rest of the EPPO region, natural spread is not considered as a significant pathway for entry. Entry into Kazakhstan via hitchhiking on other commodities or in vehicles has a low likelihood with moderate uncertainty. 

For all EPPO countries, the most likely commodity pathways for entry are: host plants for planting (except seeds, tissue cultures, pollen); round wood and sawn wood of hosts (with or without bark); and cut branches. Long distance dispersal via vehicles is not expected to be a likely entry pathway.

For EPPO countries other than Kazakhstan, the likelihood of entry was overall moderate with a moderate uncertainty (for countries where import of Malus plants for planting is not prohibited) and low with high uncertainty (for countries where import of Malus plant for planting is prohibited; corresponding to the rating for cut branches), and linked to commodity pathways only. 

The likelihood of establishment of A. mali outdoors in the EPPO region is considered very high with low uncertainty. Malus domestica is widely distributed in the EPPO region and M. sieversii is widely present in Central Asia and the climatic conditions are not considered to be a major limiting factor for the establishment of the pest where Malus hosts are present. The pest has a life cycle which can be completed within 1 or 2 years depending on climatic conditions. The northern limit of the potential area of establishment cannot be defined precisely. The critical parameters would, however, be the presence of hosts and whether cool summer temperatures allow emergence and reproduction of adults (thermal requirements are not known). 

The magnitude of spread was rated as moderate with a moderate uncertainty. The pest has limited natural dispersal capacity but there may be longer ‘jumps’ through human-assisted means (traded commodities or vehicles), that could lead to multiple outbreaks and increase the magnitude of spread. Malus plants for planting in trade are likely to be young plants, which can be infested, but the likelihood of spread is expected to be reduced due to management at the nurseries.

The impact (economic, environmental and social) in the pest’s native range in China was rated for M. sieversii as high with a low uncertainty and for M. domestica moderate with moderate uncertainty. Limited or no data were found on the situation and/or impact on other hosts, or in other areas where the pest occurs (Mongolia, Russia, Democratic People's Republic of Korea, Republic of Korea). The magnitude of potential impact in the EPPO region was rated for M. sieversii as high with low uncertainty and for other Malus hosts (including M. domestica) as moderate with high uncertainty. The potential impact was rated especially high for M. sieversii forests in Kazakhstan because this species is a valuable genetic resource. 

In China, sanitation pruning and chemical insecticide applications are the most efficient control measures in orchards. Sanitation pruning could also be applied in the EPPO region. If A. mali is introduced again into the EPPO region, available insecticides are very limited, and biological control agents are not yet available. 

Because of the high damage recorded in China and of the importance and widespread distribution of hosts in the EPPO region, the EWG recommended that phytosanitary measures may be considered. 

In the context of climate change, the area of potential establishment of A. mali might extend northwards and to higher altitudes. Increased temperature, frequency and duration of severe droughts might increase the negative impact of the pest.

Phytosanitary Measures to reduce the probability of entry: 

Risk management options have been identified and evaluated for host plants for planting, cut branches, round wood and sawn wood of hosts. The EWG recommended that they should be applied to the genus Malus (Section 7). If more scientific information confirming new host status become available, the same measures should be recommended for these additional hosts. With the currently available information, some countries may decide to regulate unconfirmed hosts to achieve a higher level of protection (Table 7.1). A number of apple wood commodities from China are available to consumers on the internet for the purpose of barbecue and smoking, and the EWG recommended that such internet trade should be placed under scrutiny. ISPM 15 phytosanitary measures are considered to be sufficient for wood packaging material.