Abstract:

To provide a basis for exploring the condition of latent infection of strawberry leaves infected by Colletotrichum fragariae, we studied the morbidities and the differences of infection characteristics of strawberry leaves infected by Colletotrichum fragariae in vitro by regulating the indoor temperature and humidity. The results showed that: the combinations of temperature and humidity of 25℃/85%, 20℃/80%, 15℃/80%, 10℃/80%, 15℃/75% and 10℃/75% all could cause disease after being inoculated 7 d, however the treatment of 10℃/70% could cause slight disease after being inoculated 28 d. The differences of infection characteristics showed that: 25% of conidia germinated after being inoculated 6 h of treatment of 25℃/85%; after 12 h, appressorium began to form and the formation rate was 16%; after 48 h, sporadic disease spots began to appear on the leaves; after 7 d, a mass of tissue cells of leaves began to decompose, and the disease index was 39.07; in the treatments of 10℃/70%, after 1 d, 2.88% of conidia germinated; the germination rate of the conidia was 100% and 8.83% appressorium began to form after being inoculated 24 d; after 28 d, sporadic disease spots began to be appear on the leaves and the disease index was 1.85; after 42 d, a mass of tissue cells of leaves began to decompose and typical anthracnose disease spots were found on the leaves. In conclusion, 10℃/70% is close to the baseline of temperature and humidity condition of strawberry leaves infected by Colletotrichum fragariae, and the incubation period can reach 28 d under the condition.

Key words: Strawberry, Colletotrichum fragariae, Temperature and Humidity, Appressoria, Latent Infection, Disease Index