This chapter presents an overview of diseases that have been or could be particularly significant to avocado production, i.e. algal spot, anthracnose, Armillaria root rot, bacterial canker, bacterial blast, bacterial soft rot, blackstreak, Cercospora spot, Dothiorella/Colletotrichum fruit rot complex, 'Duke 6' stem pitting, Phytophthora cankers, Phytophthora root rot, scab, sooty blotch, sooty mould, stem-end rot, sunblotch, Verticillium wilt, and white root rot (Rosellinia root rot). The symptoms, epidemiology, causal organism(s) and control for each disease are also discussed.
This chapter provides an in-depth review of important diseases affecting avocado production throughout the world. The importance of understanding the interaction of plant pathogens with their avocado host in order for the development of disease management options is also discussed.
Rootstock studies conducted on ‘Hass’ avocado found that rootstock
had a significant impact on postharvest anthracnose susceptibility. This is
the first record of such an effect for avocado. The severity and incidence of
anthracnose was significantly lower on ‘Hass’ grafted to
‘Velvick’ Guatemalan seedling rootstock compared with the
‘Duke 6’ Mexican seedling rootstock. Differences in anthracnose
susceptibility were related to significant differences in concentrations of
antifungal dienes in the leaves and mineral nutrients in the leaves and fruits
from trees grafted to different rootstocks. Leaf diene concentrations were up
to 1.5 times higher in ‘Hass’ trees on the ‘Velvick’
than the ‘Duke 6’ rootstock. In ungrafted nursery stock trees,
diene concentrations were around 3 times higher in ‘Velvick’ than
‘Duke 6’ leaves. The ‘Velvick’/‘Hass’
combination also had a significantly lower leaf N concentration, a
significantly higher fruit flesh Mn concentration, and significantly lower and
higher leaf N/Ca and Ca+Mg/K ratios, respectively. A significant
correlation (r = 0.82) between anthracnose
severity and skin N/Ca ratio was also evident.
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