Crocus August 2019

[fermi de Sousa]

Crocus flavus - first two pics taken a couple of days ago, the second shows why I often miss the first flowers - they are the same colour as the fruit of the Mexican Hawthorn which fall at the same time!
Today there was a bit more brightness so the flowers were open 
cheers
fermi

[Yann]

very nice contrast with the leafs

[fermi de Sousa]

very nice contrast with the leafs

Hi Yann,
yes, there's also some tulipa foliage in there as well
cheers
fermi

[Janis Ruksans]

I'm still repotting crocuses - quite late comparing with other years. Only on Sunday finished harvesting of autumn blooming species and regardless of dust dry soil in pots some already formed long shoots and even small "buttons" of root initials. At present champions in shoot length are Crocus damascenus. Of course. I don't know how long at present could be shoots of some early speciosus which were repotted with long shoots already in July, but still no flowers. I will start watering only when will finish repotting of autumn bloomers. Still left most of pallasii group, melantherus, boryi and laevigatus, hope to finish autumn blooming crocuses this Sunday.
Last year I experimented with planting depth. I use 20 cm deep pots and usually my corms are placed 5-7 cm deep. Last autumn many corms were planted 10-12 cm deep. From autumn blooming species really benefited only 2 species - pulchellus and boryi. I never had so large corms in those two species, but there were no splitting at all. Other species were very variable and I didn't observed great advantages from such planting. Small sizes seem that even didn't like this.
Some autumn bloomers formed huge corms and champions this year was hatayensis, haussknechtii and mathewii. In my 15x15 cm (6x6 inches) size pots was possible to place only 5-6 corms of hatayensis and haussknechtii and only 8 of mathewii (see attached picture).
On other pictures - corms of various C. damascenus stocks showing shoot length.
About other pleasant/unpleasant news in later posts. I'm very tired in evenings to work at computer. Still left for harvesting some 600 pots of spring blooming crocuses and a lot of other bulbs. And all must be planted back...

[Janis Ruksans]

Spring crocus harvesting still isn't finished. At present I can tell that only Crocus candidus grew better if was planted deeply.Closely related olivieri showed no improving from deep planting, about balansae difficult to judge at present. From those which naturally are growing very deeply I at present harvested only Crocus sarichinarensis from C. flavus group - they were planted even deeper - at 15 cm, so below corms left only 5 cm of substrate - results fantastic - I never before had so huge corms of this species. Others "flavus" relatives still are not harvested.

Another experiment I did with soil acidity. I never was successful with such species as yalovensis (sin. violaceus, pestalozzas v. violaceus) and some others. Last year I planted this and some other crocuses in very acid soil mix adding acid peat moss to my usual mix in proportion 1:1 - results simply fantastic. So good crop I never berfore had. As I wrote earlier this spring I had pH testing equipment with me to Portugal and Greek Macedonia, where I found that C. duncanii, carpetanus, veluchensis naturally grew in soil with pH around 5 (same was observed with Narcissus cyclamineus). Now all those species are potted in special very acid sdubstrate (I suppose that in Europe where in some places natural peat moss is not available, can be used Rhododendron mix).

On picture my table on wheels for transporting pots inside greenhouse (my polytunnel is 40 m long).
.

[Janis Ruksans]

Today I finished repotting of pallasii group crocuses and started with C. melantherus samples. Still left boryi and laevigatus and that means that on Saturday I will return to spring bloomers. Hope next week to finish with crocuses and then will start other bulbs. Few colchicums already blooms in boxes - for those is already too late, but I’m not more so powerful.

And now came time for unpleasant news. This summer new pest was identified on crocuses. It is thrips. Earlier it seriously damaged and was great problem for Gladiolus growers here, but never before was seen (at least by me) on crocuses.

Although in average crocus crop this season was very good and better than last year, on corms of several species I observed brown dots and spots. Really I saw such spots before, too, but as crocuses not much suffered and well developed afterwards I didn’t gave great attention to them, but this year on some species many corms had such damage and some were heavily damaged. Accidentally (and fortunately) one of chief phytopatologists of Estonia visited my nursery on way back from conference in Latvia. I showed her damaged corms and new shoots of Crocus cappadocicus (one of species, which had greater number of damaged corms). She immediately identified this as damage done by thrips (Thysanoptera), which became common with changes of climate. Thrips likes hot weather, but it is comparatively easy to control.

Now I understand why crocuses got from nurseries in West Europe and from some very famous crocus growers and explorers didn’t grew well with me, but seedlings of same species or stock grew perfectly. Summers in W Europe are much hotter and that is liked by thrips. Crocus corms came to me together with trips. Last two summers here were unusually hot, too and thrips liked this.
Not all species suffer in same degree. I had pot with some crocuses collected on Naxos Island in Greece. Between 16 corms named as “cancellatus aff.” were two corms of C. pallasii aff.  All 14 corms of cancellatus had perfect corms, but both pallasii had few small brown spots. Mostly with me suffered C. hadriaticus and crocuses from C. pallasii group. In other species were some damaged corms, but really few. Completely was lost very beautiful cultivar of C. mathewii ‘Brian Mathew’ - from 32 corms planted in two pots no one alive! Seem that thrips was followed by Fusarium.

I suppose that few famous crocus explorers from Germany lost their collections not from Rhyzogliphus mite, as they supposed, but just from thrips. Really I only twice found one mite on died or damaged crocus corm and once several on Scilla bulb. Scilla after treatment with acaricide completely recovered.

On attached pictures you can see thrips damage on different crocus species. Of course so heavily damaged corms were all destroyed (burnt), slightly damaged got chemical treatment and I treated with Phastac healthy looking corms, too. How it is done - in next entry.

[Janis Ruksans]

So now I’m treating all my crocus corms with Phastac (I’m professional gardener and have licence to use such chemicals - systemic insecticides/acaricides). To avoid skin contact (I can’t work in glows), I’m placing corms in pots and then spraying over them with 0.2% strong pesticide and after that immediately cover them with substrate and place pots in beds. See attached pictures.

[Janis Ruksans]

The first crocus flower this season - Crocus ilgazensis.

[Yann]

Aphids are my number one enemies in the greenhouse, they can stay inside the compost and infect the bulbs without suspicion of attack.
Slugs are those eating in 20 secondes the long awaited crocus blossom...that's nature.