DECEMBER in the garden

I think most of you will have planted by now. Most areas will be over the frost danger and may even be experiencing temperatures 20 degrees and more. Your stakes will be in, compost down and plants anywhere from 1cm high to 20 cm or so. As soon as you have foliage around 10cm high you can assume there will be good root formation as well. At this point it will be a good idea to put your fertilizer premix and some epsom salts around the root zone. Tomatoes have a similar requirement to dahlias so tomatoe fertilizer could be used instead of the premix.

Replace any washed out slug bait and get a round of bug spray on. Ripcord is my favourite prior to bud formation.

December for us here in the Tararua district can be very wet, so I get busy spraying with the baking soda fungal spray as well. The fungal issues are most prevalent in the wet, warm conditions.

Fungus can affect leaves, tubers and soil. Tuber rot will appear as wilting leaves and failure to thrive.

Have a little poke around with your fingers carefully over the tuber. If it is mushy, throw it out.  Don't be tempted to take a cutting off the top as usually the stem will have the fungus in it too. You can take a little of the dirt that was around it out too.

Fungal smut can start as small yellow spots, usually on the lower leaves, which can be confused with some viral issues. Take affected leaves off, keep spraying and if it is fungal you will get on top of it. Smut spots also get bigger and go to a greyish, brown colour and will often get a hole in the centre. Wash hands and tools between each plant!

If the spots are viral they will often be anywhere on the plant and wont respond to treatment. Viral spots can be accompanied with other chlorotic areas on the leaf. Wash hands after handling. Maintain top notch hygiene with hands and tools as virus in particular can spread like covid. Treatment for virus is removal. If you know the plant is virused, don't delay with removal. Wait and see will only mean you have even more plants for removal later. It shouldn't be necessary to to remove dirt from where the plant was taken. Do not compost!

For further online information, I recommend googling Dr. Pappu's excellent write up and pics from Washington State University. There is also an article by our own Dr. Keith Hammett on the NZ national dahlia site that is well worthwhile having a look at.

For more in depth local virus information , the wonderful Becky Cochrane is available to contact.

I have pulled many plants from my own garden so far (2023/24) with virus. Very frustrating.  It is critical to maintain bug spray. It only takes a few thrips/aphids to spread virus throughout your whole dahlia patch. If in doubt throw it out.