Are you all nervous about this weather? I am. Buds are opening very quickly and we’re still in early April. The chances of a frost/freeze yet this spring are very high. Hopefully, the cooler weather after this weekend will slow development a little, but everything has lost some cold tolerance.
Pruning – Ideally, pruning should be finished before buds break. Most farms I’ve been on are done or nearly so. Be sure to prune out (and destroy) any stem galls. We are seeing increasing incidence of this pest since summer SWD sprays kill the natural enemies of the stem gall wasp. Also, prune out dead or diseased canes, as these contribute inoculum for new infections.
Dormant Sprays – depending on where you are, the window for dormant sprays is closing, as buds open. If you have had issues with anthracnose, cane blights, or scale, a dormant oil or lime sulfur spray can help. If development has progressed to where you risk burning the new tissue, copper products or a sterilant like Oxidate or Rendition could be used, but may have lower efficacy.
Weed Management – If you use wood chip mulch for weed suppression, and the layer is breaking down, try to get fresh mulch on before the weeds get established. For herbicides, Casuron 4G must be applied before May 1st. If you are applying it in April, make sure to apply before soil temperatures exceed 45 degree F and before any annual weed seeds germinate – this window is probably closing as well! Casoron CS can be applied a bit later but still needs to be incorporated by rainfall before weed germination; it is labeled for 1 year old blueberries. Casoron controls annual grasses and broadleaves, as well as some perennial grasses. Follow Casuron with a post-emergent such as paraquat to kill pre emerged weeds or apply glyphosate when weeds are actively growing. Princep, Devrinol, Axxe, Solicam or Sinbar can all be applied for pre-emergent weed control. If you have a nutsedge problem, consider using Sandea.
Managing pH – if the soil pH is higher than 5.2, add 200 lb/ac of elemental sulfur every year until it is back in range. Remember that the target is 4.5. It takes time for the sulfur to lower the pH, so don’t let it get too high before trying to correct. If you are irrigating blueberries (highly recommended!), it is important to check the pH of the irrigation water, as water over 6.0 can quickly neutralize the acidity in the soil. Water with high pH or bicarbonate levels can be acidified with sulfuric, nitric, phosphoric or citric acids (only citric is allowed in organic systems).