Bacterial canker disease of sweet cherry continues to be a persistent and economically important disease of sweet cherry in the Pacific Northwest. The pathogen primarily overwinters in cankers.
Removing cankers is essential to reduce the inoculum, especially in young orchards, where heading cut infection in the spring always leads to canker development as fresh pruning wounds provide direct entry points for the bacterial pathogens.
One of the most common questions growers ask is how far to cut below a visible canker to completely remove the canker and associated pathogens. A recent study found that bacteria can still be recovered 3 inches (≈7,6 cm) below visible canker but not 5 inches (≈12,7 cm) (Fig. 1), therefore, removing approximately five inches (≈12,7 cm) below the visible margin of a canker during hot/dry conditions can effectively remove the pathogen from further infection and limit disease spread during pruning.
In addition, allowing pruning wounds to dry and heal before the onset of cool, humid, or wet conditions is an effective cultural strategy for reducing infection risk. It is also beneficial if pruning tools are sanitized after every cut as pruning tools could transfer bacterial inoculum from infected to healthy tissues, leading to new infection.
Photo of bacterial canker infected tissue (A) and bar graph of recovery rate on y-axis versus pruning margin on x-axis (B)
Figure 1. Recovery of Pseudomonas syringae pv. syringae (Pss) from sweet cherry shoots at increasing distances below visible canker symptoms. Tissue was sampled from four positions (A-D) located 1, 1.5, 3, and 5 inches (≈2,5; ≈3,8; ≈7,6; ≈12,7 cm) below the visible canker margin from 38 shoots infected with the Pss S2 strain.
Bacterial recovery was 100% at 1 inch (≈2,5 cm), 97.4% at 1.5 inches (≈3,8 cm), 18.4% at 3 inches (≈7,6 cm), and 0% at 5 inches (≈12,7 cm).
Sheersa Manna and Frank Zhao
WSU Plant Pathology
Source: Washington State Tree Fruit Extension, Fruit Matters, treefruit.wsu.edu
Image source: WSU
18 Mar 2025
The excessive use of chemical fertilizers in cherry cultivation causes environmental problems, including the release of nutrients and soil degradation. These excessive inputs often exceed the actual needs of the trees, causing nutritional imbalances and inefficiencies.
20 Oct 2023
The problem is the hours of cold. We speak of temperatures below 7° or 8°; and these temperatures do not occur on the Peruvian coast. Today, with the varieties tested, it is not possible to produce cherries in Peru; you get to flowering, but then the fruit does not set.
11 Mar 2026
Chile’s cherry sector is facing a turning point after years of expansion. Rising production and a surplus of fruit in the Chinese market are putting strong pressure on prices, forcing growers and exporters to adapt to a more competitive and less profitable environment.
10 Mar 2026
A field trial in a cherry orchard in Izmir, in Turkey’s Aegean region, shows that bumblebee pollination with Bombus terrestris improves cherry size and weight. Results highlight larger fruit, fewer cherries per kilogram and higher profitability for export-oriented growers.
