Yellow/Dry leaves - Growing hops in warm/hot climate

[perastikos]

June of 2015 I purchased and planted 4 hop varieties, hallertau, perle, cascade and magnum. I live in Greece and the summer is quite warm/hot here. The hops came in small pots, already established small plants and they made it through the first year.
I planted them under some big olive trees, in order to minimize the sun. The hops grew well, got up to 2m/6.5ft and they even produced some a few baby hop cones, just a handful.

First year:


This spring I decided to dig them up and replant them in another location and farther apart between them. They have grown very well, especially the cascade, but the leeves at the bottom of the plants have been becoming yellow, dry up and eventually fall off.
Cascade had developed burs since the beggining of June.
I am watering every day with a dripping system. Sometimes twice a day, because the soil does not hold much of the water and it dries up.

The upper plant/leaves part of the plant is very good, but i'm afraid it will go bad untill the harvest.





From left to the right. Hallertau-Perle-Cascade-Magnum.
You can see there that the bines on the first on the left (hallertau) has been stripped of leaves. They have dried and fall off. On the other hand Perle and Cascade have new bines emerging from the soil, which I guess is a good thing.


This is cascade. The third from the left


Anyone has a clue?
Is it a matter of heat/sun? Is it a disease? Nutrient deficiency? Overwatering?

 

[friarsmith]

A few thoughts:

Turn off the water for 2 days. Then dig carefully around the root crown down to about 6-12 inches. If the soil at that depth is dry, then you should incorporate some compost/organic matter/manure in the off-season at this depth up to the surface to improve vertical/downward drainage (as opposed to lateral runoff) and moisture retention around the roots. Sounds counter intuitive, but it works. If the soil is slightly damp when you dig, then watering amount is probably not the issue.

When the plants set cones, it's not uncommon to see some yellowing of the lower leaves due to phosphorus/potassium deficiency. That's because the plants are using these nutrients for setting cones as opposed to foliage maintenance. Feeding your plants with a blooming agent (see link) will help.

FWIW, I feed my hops with Nitrogen-heavy fertilizer for the first 30 days after the sprouts emerge in the spring, then switch to a blooming agent about 3-4 weeks before the burrs usually appear, which means switching to the blooming agent around July 1 in the midwest US.




http://www.homedepot.com/p/Alaska-3...j_1CzhVFJW3RqCiJyUCg4aAoyL8P8HAQ&gclsrc=aw.ds

 

[brewcat]

How hot is hot? Hops in Yakima Valley are routinely grown in high heat.

Some yellowing of bottom leaves is a good sign with burr onset. Less nitrogen is good during cone formation.

I also don't really worry about stripped bottom leaves after the plant gets so high. It provides better airflow and avoids possible mildews.

 

[perastikos]

I did add fertilizer for 40 days, mid May to end of June. Cascade burrs had already appeared.
The ingredients were these:
20%N,
5%P2O5
10% K2O
3%MgO
5% S
0.3% B
0.3% Fe
0.1% Zn
Friarsmith, since 1st of July I didn't add anything else, just water. At that time, I recall that there were 2-3 yellow leaves, drying at the very bottom. But since then it's migrating upwards.

With hot climate I mean temperatures, for example this week: lowest 21-37C/70-99F. Humidity is on average, around 60% for the summer.
Brewcat, I guess that Yakima Valley has the same temperatures, from a little research I did online. The company I bought my hops from was in Germany. They advised me to water them very well and frequently, nonetheless they would be struggling in my climate. I guess it depends on the variety as well.

 

[thaymond]

I did add fertilizer for 40 days, mid May to end of June. Cascade burrs had already appeared.
The ingredients were these:
20%N,
5%P2O5
10% K2O
3%MgO
5% S
0.3% B
0.3% Fe
0.1% Zn
Friarsmith, since 1st of July I didn't add anything else, just water. At that time, I recall that there were 2-3 yellow leaves, drying at the very bottom. But since then it's migrating upwards.

With hot climate I mean temperatures, for example this week: lowest 21-37C/70-99F. Humidity is on average, around 60% for the summer.
Brewcat, I guess that Yakima Valley has the same temperatures, from a little research I did online. The company I bought my hops from was in Germany. They advised me to water them very well and frequently, nonetheless they would be struggling in my climate. I guess it depends on the variety as well.

From what I have noticed with my plants, once the cones form on the side arms of the plants, the leaves at the bottom 1/4 of the plants seem to yellow and fall off. The nutrient stores from the bottom of the plant are being sent to the hop producing portion of the plant, Which is primarily the top half. If your top leaves are looking good, your water schedule is regular (or it rains frequently enough), and they have been properly fertilized, you are probably noticing the plant transferring it's energy to the top canopy.

If you notice downy/powdery mildew or other disease like symptoms other than yellowing, or pests on your plants, it might be more troublesome. From what I see in the pictures you provided and from your description of watering and fertilizing, it could just be the plant maturing for cone development. You could certainly add more P/K fertilizer to help with yellowing, as friarsmith said.

 

[perastikos]

Thank you all for your replies.