Annual Progress Report on Malting Barley Research March, 2002

44
made on culture media showed that barley nodes recovered, irrespective of treatment,
were readily colonized by F. graminearum and C. sativum. Other pathogenic and nonpathogenic
Fusarium species were also recovered from nodes, but less frequently.
Recovery of F. graminearum (FG) and C. sativus (CS) were significantly (P>0.01)
reduced in burned residues (FG, 6%; CS, 4%) in comparison with the non-burned
residues (FG, 42.7%; CS, 13%). Recovery of both pathogens was almost nil from
visually charred residues. Recovery of F. culmorum, F. avenaceum, and F.
sporotrichioides, and other fungi followed a similar pattern. Our data show that residue
burning can reduce the inoculum potential of pathogens present in residues, and may
assist in the management of destructive diseases such as Fusarium head blight.
Our data shows that wheat and barley residues left on the field after harvest were
colonized by F. graminearum, and C. sativus, which indicates that crop residues provide
a suitable reservoir for the survival of these pathogens between growing seasons. The
practice of burning residue reduced the amount of residues left on the soil after harvest by
two thirds, and substantially reduced the population of F. graminearum, and C. sativus
present in straw. These results agree with those found by Reis and Abrao (1983; Plant
Disease, 76:1088-1089) and Bateman et al. (1988; Ann Appl. Biol., 132:35-47). These
findings confirm the role that residues play in the epidemiology of foliar diseases of
barley and suggest that residue burning, even where residues are not totally destroyed,
may be useful in the management of destructive diseases such as Fusarium head blight.
Influence of Mist-Irrigation on Fusarium Head Blight and Seed Characteristics of
Barley:
Fusarium head blight levels in field nurseries are often variable and this variation
complicates our ability to obtain consistent results when screening parental sources of
barley and segregating populations in search of resistant germplasm. Field experiments
were conducted in 2000 and 2001 to evaluate examining the management of
supplemental moisture volume in FHB screening nurseries. The main objective of this
study was to determine the effect of different daily mist-irrigation volume treatments on
several variables that are used to estimate FHB-severity. These data were compared to
inoculated barley plots with no mist irrigation, relying only on seasonal dew and rainfall
to promote FHB infection.
The experimental design was a randomized complete split-block for each mist-irrigation
(MI) volume treatment. Split-block treatments were inoculated vs. non-inoculated. The
barleys examined were MNS 93 (resistant, R), MNBrite (moderately resistant, MR),
Robust (susceptible, S), and Stander (S). Row spacing was 0.3 m and length of a plot-row
was 2.4 m with two rows per plot. At heading, a suspension, containing 100,000
macroconidia ml-1 was applied using a CO2 powered backpack sprayer with TeeJet
SS80015 flat-fan nozzles operating at a pressure of 2.8 kg cm -2 . Inoculum suspensions
were mixed with 2 ml Tween-20 l -1 . Following the initial inoculation, mist irrigation was
applied each day beginning at 5 PM and concluding the following morning at 8 AM with
a total of 8 mist irrigation intervals per night. Water volume dispensed in each of the
blocks was 2, 4, and 8 mm of water, respectively. Mist irrigation was terminated the day
FHB assessments were conducted. Disease assessments were made in the field 14-18
days post-inoculation (PI) and plot seed was harvested at crop maturity. FHB disease