Bay sucker ... Small nymphs suck the sap and cause leaf edge roll. If the plants are for immediate sale, spray with a short harvest interval product such as SB Plant Invigorator or Stalwart (SOLA 2006-3285). Otherwise, use Hallmark with Zeon Technology or Decis.
Roses Adding a wetting agent with an eradicant spray application can usually control roses with stubborn powdery mildew. Products like Fungaflor 100 EC or Nimrod with wetter normally shift those stubborn areas. On ornamental trees you can use Corbel but watch the warm days with this product as it can cause foliage damage.
Whitefly Do you experience a distinct lack of black scales on plants where whitefly control by Encarsia is used? Don't give up but look closer at what you do. Spraying bifenthrin, even three months earlier, can destroy predator populations. Temperature too can make a difference with one or two low night temperatures putting them off. Place cards so they are not directly irrigated and ensure the black-scale side points north, away from direct sunlight. This will make all the difference to initial hatching. Consider introducing banker plants of Lavatera where a steady population of both whitefly and Encarsia can exist, acting as an Encarsia spring board to your crop.
Shot hole The current wet spell is still encouraging bacterial shot hole infections on laurels. Spray again this week with Cuprokylt to avoid high infection rates developing.
Stem cankers Start planning your lifting programme now. A range of tree crops are vulnerable to stem canker but maintaining cleanliness of the stems and transport system after lifting seems to reduce the risk of infection. The over-winter storage conditions can also affect the state of the tree so try to store the problematic subjects under cover in winter.
Botrytis Check for this disease this week on crops spaced close together or those with dense foliage. Spray with Rovral WP or Frupica SC.
Scab Continue to be on a close weather watch to check on scab periods. We have had some in the last week. Check Malus, Pieris, Chaenomeles and Crataegus leaves. Eradicants such as Radspor FL or Barclay Dodex will control existing scab growth and Topas and Systhane 20EW have a seven- to 10-day protectant effect.
FRUIT ON PLANTS
A reminder to make sure you remove the fruit on fruit trees before tree sale to comply with pesticide and edible crop regulations.