There have been many studies conducted in other countries on control of mouldy core, particularly on the variety Red Delicious where Alternaria is generally the main cause of the problem. Application of fungicides between first flower and petal fall reduced the incidence of mouldy core in most experiments. Not all fungicide trials were successful and this may be related to the fungi responsible for mouldy core. Treatments found to reduce the incidence of mouldy core in overseas trials included carbendazim, mancozeb (Karamate), various DMI fungicides (e.g. myclobutanil), vinclozolin (Ronilan), strobylurine fungicides (e.g. azoxystrobin) and potassium phosphite (see tables below).
In a more recent AHDB Horticulture UK funded study (Project TF 184) in 2009, fungicide trials conducted in two commercial orchards found that sprays of either Bellis (pyraclostrobin + boscalid) or Switch (cyprodinil + fludioxonil) at full bloom and 10-14 days later, had some effect in reducing mouldy core compared to where no treatments were used.
Choice of fungicide that may control mouldy core - efficacy factors
| Active ingredient | Trade name (examples) | Fungicide group | Typh safety | Other diseases controlled/partly controlled |
|---|---|---|---|---|
| cyprodinil + fludioxonil | Switch | anilinopyrimidine + cyanopyrrol | safe | Scab, storage rots, canker |
| mancozeb | Karamate Dry Flo, Penncozeb WDG | dithiocarbamate | harmful | Frequent use suppresses mites |
| myclobutanil | Systhane 20 EW | triazole (DMI) | safe | Scab, mildew |
| pyraclostrobin + boscalid | Bellis | strobylurine (Qol) + anilide | safe | Scab, mildew, storage rots, canker |
Choice of fungicides that may control mouldy core - safety factors
| Active ingredients | Hazard | Harvest interval (days) | Max no. sprays | Buffer zone | |||
|---|---|---|---|---|---|---|---|
| Human | Fish/aquatic life | Bees | Width (m) | ||||
| cyprodinil + fludioxonil | a,c | t | u | 3 | 3 | 30 | |
| mancozeb | ir | t | u | 28 | Varies with product | 40 | |
| myclobutanil | h | t | u | 14 | 3 - Only 1 applied in August | 20 | |
| pyraclostrobin + boscalid | h | t | u | 7 | 4 | 40 | |
d = dangerous; h = harmful; ir = irritating, a = may cause allergic reaction, t = toxic
PH = post harvest; Pre bb = pre-bud burst, sm=statutory minimum of 5 m for broadcast air assisted sprayers
u=uncategorised/unclassified/unspecified, c=closed cab required for air assisted sprayers
Avoiding fungicide resistance
The risk of resistance is low as a range of fungicide products are used and intensive spray programmes are not used.