PLANT HEALTH MONITOR

Press, 10 January 1986, Page 19

PLANT HEALTH MONITOR

MAF

The new year brings a change of emphasis from cereal plant to grain storage and pastoral problems. Growers can do very little now to improve crop yields, but a lot to ensure storage and pasture losses are kept to a minimum. CEREALS

® Now is the time to check cereal crops for diseases that can carry over and cause losses in next season’s crops. The main one to look for is take-all which shows up as white heads in maturing crops. Wet weather late in the season delayed take-all infection and infected plants are not as stunted as they could have been.

Also note areas of footrot, and refer to Aglink FPPSSI, and Cereal AgPhoto pages 27 (footrot) and 24 (takeall) for a description of the symptoms. Detection now' will assist in crop sequence planning for next season.

® Fungi that cause black point are present in wheat heads and may infect the maturing seed coat if the weather turns wet. Some cultivars such as Kopara, Bounty and Crossbow are more susceptible. The wheat pricing index this season includes black point assessment.

® The bacterial disease basal glume rot is common

in the cultivar Weka this season. It causes blackening of glume and stems and rotting of leaf ligules causing premature leaf death. Little information is available on the effect this disease has on crop yield or quality, but it may reduce grain weight. See Cereal AgPhoto page 21 for description of symptoms. ® Glume blotch is common in the cultivars Oroua and Advantage, causing considerable flag leaf damage especially in late maturing crops. Although little head damage is apparent now, more wet weather could cause some grain rotting in these cultivars.

® Stripe rust infection in the heads of cereal crops is associated with grain shrivelling. The addition of other stresses, especially hot dry weather, will cause further shrivelling of rust infected grain.

® Fusarium head blight, a relatively uncommon disease, has been found in many crops this season because of the wet weather. Unfortunately most of these problems are a reflection of wet weather conditions, and no chemical controls are available. In future adequate control may be obtained by the use of resistant cultivars and different cultural practices.

® Leaf rust may be a problem in late sown barley crops. Keep it under control by regular spraying with Bayleton or Tilt. CEREALS AND SMALL SEEDS ® Army worm populations continue to be a problem. Early recognition is necessary to prevent serious damage. If greenish-brown caterpillars with dark brown stripes on the sides can be easily found during the day, apply an insecticide promptly, preferably during the evening using as high a volume of water as possible. PASTURE ®lf excessive pasture growth continues, it will be a good opportunity to reduce infestations of both barley grass and nodding thistle. By maintaining a dense pasture sward over the next few weeks, reinvasion of these weeds can be significantly reduced.

© It is highly probable that both grassgrub and porina damage will be severe and widespread this winter. Grassgrub adult flights were particularly heavy and high juvenile survival is expected due to a moist November and December.

Be prepared to monitor porina early, using the board technique described in AgLink FPP 588.