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Crop Watch

June 8, 2018
By BOB STREIT , Farm News

Field observation

The common observation

made by most ag people is

that they have never seen the

corn crop grow so fast in a

short period of time as the

plants did this year. Getting

25 plus GDUs per day for

about two weeks will cause

very rapid growth. Will the

stalks be as strong this year

or might they be weaker?

We could see a difference

versus normal, and soil test

levels for Ca and K could be

an influencing factor.

In many fields in central

Iowa the plant have reached

the late V4 moving into the

early V5, which is when

rapid growth occurs. This is

also when the cautions about

using phenoxy are justified.

It seems that more corn

growers are using Dicamba

based products on corn to

take care of some of the

problem broadleaf weeds.

This was reminiscent of the

time when farmers would

wait until about May 15th

before planting beans, so

would begin spraying corn

before the beans emerged.

They knew their drift or inversion

problems were minimized

if very few beans

were emerged in their neighborhood

at the time of

Dicamba applications.


Early in the season the

daily amounts of precipitation

used by the plants is

very small. As the plants

grew from the V6, and later

the V8

stage the

daily usage



peaking at



Stored and





those daily

requirements thru April

and May. Then as root uptake

increases the immediate

demand for moisture is typically

met by rainfall.

Insect indicators

The first fireflies are beginning

to appear now and

their little lights can be seen

blinking at dusk. Concurrent

with their appearance is our

normal CRW egg hatch.

This typically takes place

when 720 to 730 GDUs

have accumulated. So depending

on location within

the north/south heat unit

charts expect the first root

feeding to start. This is a labor

intensive process that

normally involves a spade or

sand shovel, buckets and a

good higher pressure hydrant.

It takes time to wash

off the roots to look for feeding

damage, and even more

time and patience to find the

very small larvae.

And if you do find them

the appropriate question is

what could be done to remedy

the problem. In the past

we have seen the Neem oil

based Safe Strike diminish

the amount and rate of root

feeding. Sometimes the

small black headed larvae

move off the roots and quit

feeding. I am curious and we

will be seeing if the Chitosan

based products could cause a

halt to the feeding.

Another insect that has

been seen are the slow flying

medium-small flies that

move quite slow and don't

move much when you begin

swatting them. These are the

adults of the seed corn maggots.

They often feed on the

disked under vegetation of

small grains or weeds as the

fields were worked. I have

seen where they tunneled up

the stem of just emerged

soybeans causing them to

topple over. It takes a keen

eye or a good magnifying

glass to see the small

translucent larvae.

The bean leaf beetle numbers

were high in the first

planted fields, but now as

more fields have emerged

those populations have drifted

down to where no fields

meet the established thresholds.

Look for the holes in

the leaves and approximate

the percent of the tissue lost

to feeding.

Herbicide happenings

Two weeks ago it was

tough to find many weed

seedlings in the fields. That

is no longer the case, as there

are high counts of our common

weeds in many fields

where control was less than

expected with about six

common broadleaves.

There have also been cases

where the PPO used last

season appears to have carried

over. Expect to see

stunted, yellowed plants.

They typically survive, but

grow and develop slower.

As to the cause (s) some of

the herbicides could have

been applied after the July

1st cutoff date or the drier

conditions after application

slowed down the expected


Show me the money

plot and field day

Several of us drove thru

and took video of the plot

work being done at the

Guthrie Center research

farm on Saturday. The corn

was planted later than in the

previous seasons and was

now close to the V4 growth

stage. It looked very good.

There is an area where a

variety of inputs are being

applied in tandem or in sequence

to see which ones influence

the yield or other

traits the most. We took a

stair-step approach to see if

each pair of input products

was producing just an additive

effect or offered a multiplier

effect. For instance 1 +

1 should equal 2. But if they

equal 3 or 5 enough to be

significant, then they could

offer growers a high ROI.

When we are using several

new products the challenge

can be identifying the

product or series of products

that should receive the credit.

We expect to have a plot

showing and meeting down

at the farm around Aug 20,

or before farmers get busy

with harvest. Our March

12th meeting in Ames that

was attended by 120 note

taking growers told us that

growers were interested in

getting educated and hearing

new ideas that seem grounded.

In the meanwhile we are

assembling the BioEmpruv

and Argosy that will be applied

this week and can be

expected to keep the plants

alive, healthy and filling until

mid to late October. We

will also apply the Take- Off

signaling compound from

the Los Alamos Lab that

seems to be working well in

all crops. The Calcium silicate

product is also in the

shed and ready to be applied.

If it allows the corn plants to

be more stress tolerant and

get by with 30 percent less

water while also increasing

the RUE (radiation use efficiency)

, the boosted sugar

production should form

more bushels.

We also have the liquid

poly peptides that are giving

good results in Brazil. The

same goes to the Ensure

product, which boosts heat

and drought tolerance

tremendously. All of these

things should help build on a

fertility program that is built

on soil health and balanced

fertility which is accessed

thru the use of Verdesian

fertilizer stabilizers. This is

all good and we are expecting

big things. It can still be

a case that in the end we will

have the answers but might

wonder what some of the

questions are. But that is

how science and producers

can make significant advances.

Soybean growth

Most of the soybean

plants are now in the V2 to

V3 growth stages. In a week

it will be time for growers

who wish to increase their

bean yields to begin their foliar

programs. The goal is to

influence their architecture

and change their physiology

to form more roots, more

side branches, added pods,

shorter internodes and

stronger stems. Past yield

winners have a game plan

set up and typically follow

thru with it, adding a few

new items as their knowledge

base expands. What are

you doing different this year

to get better?

Bob Streit is an independent

crop consultant and columnist

for Farm News. He can be

reached at (515) 709-0143 or



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